CVE-2026-31555 (GCVE-0-2026-31555)

Vulnerability from cvelistv5 – Published: 2026-04-24 14:35 – Updated: 2026-09-08 08:47
VLAI
Title
futex: Clear stale exiting pointer in futex_lock_pi() retry path
Summary
In the Linux kernel, the following vulnerability has been resolved: futex: Clear stale exiting pointer in futex_lock_pi() retry path Fuzzying/stressing futexes triggered: WARNING: kernel/futex/core.c:825 at wait_for_owner_exiting+0x7a/0x80, CPU#11: futex_lock_pi_s/524 When futex_lock_pi_atomic() sees the owner is exiting, it returns -EBUSY and stores a refcounted task pointer in 'exiting'. After wait_for_owner_exiting() consumes that reference, the local pointer is never reset to nil. Upon a retry, if futex_lock_pi_atomic() returns a different error, the bogus pointer is passed to wait_for_owner_exiting(). CPU0 CPU1 CPU2 futex_lock_pi(uaddr) // acquires the PI futex exit() futex_cleanup_begin() futex_state = EXITING; futex_lock_pi(uaddr) futex_lock_pi_atomic() attach_to_pi_owner() // observes EXITING *exiting = owner; // takes ref return -EBUSY wait_for_owner_exiting(-EBUSY, owner) put_task_struct(); // drops ref // exiting still points to owner goto retry; futex_lock_pi_atomic() lock_pi_update_atomic() cmpxchg(uaddr) *uaddr ^= WAITERS // whatever // value changed return -EAGAIN; wait_for_owner_exiting(-EAGAIN, exiting) // stale WARN_ON_ONCE(exiting) Fix this by resetting upon retry, essentially aligning it with requeue_pi.
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 3ef240eaff36b8119ac9e2ea17cbf41179c930ba , < 33095ae3bdde5e5c264d7e88a2f3e7703a26c7aa (git)
Affected: 3ef240eaff36b8119ac9e2ea17cbf41179c930ba , < e7824ec168d2ac883a213cd1f4d6cc0816002a85 (git)
Affected: 3ef240eaff36b8119ac9e2ea17cbf41179c930ba , < 5e8e06bf8909e79b4acd950cf578cfc2f10bbefa (git)
Affected: 3ef240eaff36b8119ac9e2ea17cbf41179c930ba , < de7c0c04ad868f2cee6671b11c0a6d20421af1da (git)
Affected: 3ef240eaff36b8119ac9e2ea17cbf41179c930ba , < 7475dfad10a05a5bfadebf5f2499bd61b19ed293 (git)
Affected: 3ef240eaff36b8119ac9e2ea17cbf41179c930ba , < 92e47ad03e03dbb5515bdf06444bf6b1e147310d (git)
Affected: 3ef240eaff36b8119ac9e2ea17cbf41179c930ba , < 71112e62807d1925dc3ae6188b11f8cfc85aec23 (git)
Affected: 3ef240eaff36b8119ac9e2ea17cbf41179c930ba , < 210d36d892de5195e6766c45519dfb1e65f3eb83 (git)
Affected: f2a9957e5c08b1b1caacd18a3dc4c0a1bdb7b463 (git)
Affected: cf16e42709aa86aa3e37f3acc3d13d5715d90096 (git)
Affected: 61fa9f167caaa73d0a7c88f498eceeb12c6fa3db (git)
Affected: 7874eee0130adf9bee28e8720bb5dd051089def3 (git)
Affected: fc3b55ef2c840bb2746b2d8121a0788de84f7fac (git)
Affected: 4.4.255 , < 4.5 (semver)
Affected: 4.9.255 , < 4.10 (semver)
Affected: 4.14.158 , < 4.15 (semver)
Affected: 4.19.172 , < 4.20 (semver)
Affected: 5.4.1 , < 5.5 (semver)
guessed Create a notification for this product.
Linux Linux Affected: 5.5
Unaffected: 0 , < 5.5 (semver)
Unaffected: 5.10.253 , ≤ 5.10.* (semver)
Unaffected: 5.15.203 , ≤ 5.15.* (semver)
Unaffected: 6.1.168 , ≤ 6.1.* (semver)
Unaffected: 6.6.131 , ≤ 6.6.* (semver)
Unaffected: 6.12.80 , ≤ 6.12.* (semver)
Unaffected: 6.18.21 , ≤ 6.18.* (semver)
Unaffected: 6.19.11 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.5 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.5 , < * (custom)
guessed Create a notification for this product.
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.5 , < * (custom)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "affected": [
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-08T08:47:43.565Z",
          "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
          "shortName": "siemens-SADP"
        },
        "references": [
          {
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
          },
          {
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
          }
        ],
        "x_adpType": "supplier"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/futex/pi.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "33095ae3bdde5e5c264d7e88a2f3e7703a26c7aa",
              "status": "affected",
              "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
              "versionType": "git"
            },
            {
              "lessThan": "e7824ec168d2ac883a213cd1f4d6cc0816002a85",
              "status": "affected",
              "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
              "versionType": "git"
            },
            {
              "lessThan": "5e8e06bf8909e79b4acd950cf578cfc2f10bbefa",
              "status": "affected",
              "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
              "versionType": "git"
            },
            {
              "lessThan": "de7c0c04ad868f2cee6671b11c0a6d20421af1da",
              "status": "affected",
              "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
              "versionType": "git"
            },
            {
              "lessThan": "7475dfad10a05a5bfadebf5f2499bd61b19ed293",
              "status": "affected",
              "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
              "versionType": "git"
            },
            {
              "lessThan": "92e47ad03e03dbb5515bdf06444bf6b1e147310d",
              "status": "affected",
              "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
              "versionType": "git"
            },
            {
              "lessThan": "71112e62807d1925dc3ae6188b11f8cfc85aec23",
              "status": "affected",
              "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
              "versionType": "git"
            },
            {
              "lessThan": "210d36d892de5195e6766c45519dfb1e65f3eb83",
              "status": "affected",
              "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f2a9957e5c08b1b1caacd18a3dc4c0a1bdb7b463",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "cf16e42709aa86aa3e37f3acc3d13d5715d90096",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "61fa9f167caaa73d0a7c88f498eceeb12c6fa3db",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "7874eee0130adf9bee28e8720bb5dd051089def3",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "fc3b55ef2c840bb2746b2d8121a0788de84f7fac",
              "versionType": "git"
            },
            {
              "lessThan": "4.5",
              "status": "affected",
              "version": "4.4.255",
              "versionType": "semver"
            },
            {
              "lessThan": "4.10",
              "status": "affected",
              "version": "4.9.255",
              "versionType": "semver"
            },
            {
              "lessThan": "4.15",
              "status": "affected",
              "version": "4.14.158",
              "versionType": "semver"
            },
            {
              "lessThan": "4.20",
              "status": "affected",
              "version": "4.19.172",
              "versionType": "semver"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.1",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/futex/pi.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.5"
            },
            {
              "lessThan": "5.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.253",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.203",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.168",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.131",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.80",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.21",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.253",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.203",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.168",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.131",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.80",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.21",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.11",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "5.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.4.255",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.9.255",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.14.158",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.19.172",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.4.1",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Clear stale exiting pointer in futex_lock_pi() retry path\n\nFuzzying/stressing futexes triggered:\n\n    WARNING: kernel/futex/core.c:825 at wait_for_owner_exiting+0x7a/0x80, CPU#11: futex_lock_pi_s/524\n\nWhen futex_lock_pi_atomic() sees the owner is exiting, it returns -EBUSY\nand stores a refcounted task pointer in \u0027exiting\u0027.\n\nAfter wait_for_owner_exiting() consumes that reference, the local pointer\nis never reset to nil. Upon a retry, if futex_lock_pi_atomic() returns a\ndifferent error, the bogus pointer is passed to wait_for_owner_exiting().\n\n  CPU0\t\t\t     CPU1\t\t       CPU2\n  futex_lock_pi(uaddr)\n  // acquires the PI futex\n  exit()\n    futex_cleanup_begin()\n      futex_state = EXITING;\n\t\t\t     futex_lock_pi(uaddr)\n\t\t\t       futex_lock_pi_atomic()\n\t\t\t\t attach_to_pi_owner()\n\t\t\t\t   // observes EXITING\n\t\t\t\t   *exiting = owner;  // takes ref\n\t\t\t\t   return -EBUSY\n\t\t\t       wait_for_owner_exiting(-EBUSY, owner)\n\t\t\t\t put_task_struct();   // drops ref\n\t\t\t       // exiting still points to owner\n\t\t\t       goto retry;\n\t\t\t       futex_lock_pi_atomic()\n\t\t\t\t lock_pi_update_atomic()\n\t\t\t\t   cmpxchg(uaddr)\n\t\t\t\t\t*uaddr ^= WAITERS // whatever\n\t\t\t\t   // value changed\n\t\t\t\t return -EAGAIN;\n\t\t\t       wait_for_owner_exiting(-EAGAIN, exiting) // stale\n\t\t\t\t WARN_ON_ONCE(exiting)\n\nFix this by resetting upon retry, essentially aligning it with requeue_pi."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-23T16:05:19.706Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/33095ae3bdde5e5c264d7e88a2f3e7703a26c7aa"
        },
        {
          "url": "https://git.kernel.org/stable/c/e7824ec168d2ac883a213cd1f4d6cc0816002a85"
        },
        {
          "url": "https://git.kernel.org/stable/c/5e8e06bf8909e79b4acd950cf578cfc2f10bbefa"
        },
        {
          "url": "https://git.kernel.org/stable/c/de7c0c04ad868f2cee6671b11c0a6d20421af1da"
        },
        {
          "url": "https://git.kernel.org/stable/c/7475dfad10a05a5bfadebf5f2499bd61b19ed293"
        },
        {
          "url": "https://git.kernel.org/stable/c/92e47ad03e03dbb5515bdf06444bf6b1e147310d"
        },
        {
          "url": "https://git.kernel.org/stable/c/71112e62807d1925dc3ae6188b11f8cfc85aec23"
        },
        {
          "url": "https://git.kernel.org/stable/c/210d36d892de5195e6766c45519dfb1e65f3eb83"
        }
      ],
      "title": "futex: Clear stale exiting pointer in futex_lock_pi() retry path",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31555",
    "datePublished": "2026-04-24T14:35:39.211Z",
    "dateReserved": "2026-03-09T15:48:24.115Z",
    "dateUpdated": "2026-09-08T08:47:43.565Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-31555",
      "date": "2026-09-25",
      "epss": "0.00171",
      "percentile": "0.05675"
    },
    "microsoft_vex": {
      "current_release_date": "2026-09-25T02:37:07.000Z",
      "cve": "CVE-2026-31555",
      "id": "msrc_CVE-2026-31555",
      "initial_release_date": "2026-04-26T01:01:37.000Z",
      "product_status:fixed": "1",
      "product_status:known_affected": "3",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "futex: Clear stale exiting pointer in futex_lock_pi() retry path",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-31555.json",
      "version": "6"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "kernel/futex/pi.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "33095ae3bdde5e5c264d7e88a2f3e7703a26c7aa",
                    "status": "affected",
                    "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "e7824ec168d2ac883a213cd1f4d6cc0816002a85",
                    "status": "affected",
                    "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "5e8e06bf8909e79b4acd950cf578cfc2f10bbefa",
                    "status": "affected",
                    "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "de7c0c04ad868f2cee6671b11c0a6d20421af1da",
                    "status": "affected",
                    "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "7475dfad10a05a5bfadebf5f2499bd61b19ed293",
                    "status": "affected",
                    "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "92e47ad03e03dbb5515bdf06444bf6b1e147310d",
                    "status": "affected",
                    "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "71112e62807d1925dc3ae6188b11f8cfc85aec23",
                    "status": "affected",
                    "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "210d36d892de5195e6766c45519dfb1e65f3eb83",
                    "status": "affected",
                    "version": "3ef240eaff36b8119ac9e2ea17cbf41179c930ba",
                    "versionType": "git"
                  },
                  {
                    "status": "affected",
                    "version": "f2a9957e5c08b1b1caacd18a3dc4c0a1bdb7b463",
                    "versionType": "git"
                  },
                  {
                    "status": "affected",
                    "version": "cf16e42709aa86aa3e37f3acc3d13d5715d90096",
                    "versionType": "git"
                  },
                  {
                    "status": "affected",
                    "version": "61fa9f167caaa73d0a7c88f498eceeb12c6fa3db",
                    "versionType": "git"
                  },
                  {
                    "status": "affected",
                    "version": "7874eee0130adf9bee28e8720bb5dd051089def3",
                    "versionType": "git"
                  },
                  {
                    "status": "affected",
                    "version": "fc3b55ef2c840bb2746b2d8121a0788de84f7fac",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "4.5",
                    "status": "affected",
                    "version": "4.4.255",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "4.10",
                    "status": "affected",
                    "version": "4.9.255",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "4.15",
                    "status": "affected",
                    "version": "4.14.158",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "4.20",
                    "status": "affected",
                    "version": "4.19.172",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "5.5",
                    "status": "affected",
                    "version": "5.4.1",
                    "versionType": "semver"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "kernel/futex/pi.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "5.5"
                  },
                  {
                    "lessThan": "5.5",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "5.10.*",
                    "status": "unaffected",
                    "version": "5.10.253",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "5.15.*",
                    "status": "unaffected",
                    "version": "5.15.203",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.1.*",
                    "status": "unaffected",
                    "version": "6.1.168",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.6.*",
                    "status": "unaffected",
                    "version": "6.6.131",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.12.*",
                    "status": "unaffected",
                    "version": "6.12.80",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.18.*",
                    "status": "unaffected",
                    "version": "6.18.21",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.19.*",
                    "status": "unaffected",
                    "version": "6.19.11",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.0",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          },
          {
            "affectedData": [
              {
                "defaultStatus": "unknown",
                "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.6",
                    "versionType": "custom"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.5",
                    "versionType": "custom"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.6",
                    "versionType": "custom"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.5",
                    "versionType": "custom"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.6",
                    "versionType": "custom"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.5",
                    "versionType": "custom"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.6",
                    "versionType": "custom"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.5",
                    "versionType": "custom"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.6",
                    "versionType": "custom"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.5",
                    "versionType": "custom"
                  }
                ]
              }
            ],
            "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "39A57944-7654-4465-9F2B-4DC1CB18ADFB",
                    "versionEndExcluding": "4.5",
                    "versionStartIncluding": "4.4.255",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "F932A542-7872-4F86-AD1E-00CCC240C25D",
                    "versionEndExcluding": "4.10",
                    "versionStartIncluding": "4.9.255",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "C62F59A2-9EFC-4E7F-B9E7-3DFF4E885406",
                    "versionEndExcluding": "4.15",
                    "versionStartIncluding": "4.14.158",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "235BE773-4E0B-4AD6-9314-D176A65C4B73",
                    "versionEndExcluding": "4.20",
                    "versionStartIncluding": "4.19.172",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "025DC0BA-08A8-4703-AE9F-7C3D8E346A45",
                    "versionEndExcluding": "5.5",
                    "versionStartIncluding": "5.4.1",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "45E871E1-B00E-4E88-83A3-60B38EAF2B8A",
                    "versionEndExcluding": "5.10.253",
                    "versionStartIncluding": "5.5.1",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045",
                    "versionEndExcluding": "5.15.203",
                    "versionStartIncluding": "5.11",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B",
                    "versionEndExcluding": "6.1.168",
                    "versionStartIncluding": "5.16",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "CE6ED4D4-0046-4573-BFA9-D64143B6A89F",
                    "versionEndExcluding": "6.6.131",
                    "versionStartIncluding": "6.2",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "97EB19EC-A11E-49C6-9D2F-6F6EC6CB98B6",
                    "versionEndExcluding": "6.12.80",
                    "versionStartIncluding": "6.7",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "ED39847A-3B46-4729-B7CA-B2C30B9FA8FE",
                    "versionEndExcluding": "6.18.21",
                    "versionStartIncluding": "6.13",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7",
                    "versionEndExcluding": "6.19.11",
                    "versionStartIncluding": "6.19",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:5.5:-:*:*:*:*:*:*",
                    "matchCriteriaId": "EE98F46A-F7D9-4609-B6A0-882E7F0D378C",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*",
                    "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*",
                    "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*",
                    "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*",
                    "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*",
                    "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*",
                    "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*",
                    "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Clear stale exiting pointer in futex_lock_pi() retry path\n\nFuzzying/stressing futexes triggered:\n\n    WARNING: kernel/futex/core.c:825 at wait_for_owner_exiting+0x7a/0x80, CPU#11: futex_lock_pi_s/524\n\nWhen futex_lock_pi_atomic() sees the owner is exiting, it returns -EBUSY\nand stores a refcounted task pointer in \u0027exiting\u0027.\n\nAfter wait_for_owner_exiting() consumes that reference, the local pointer\nis never reset to nil. Upon a retry, if futex_lock_pi_atomic() returns a\ndifferent error, the bogus pointer is passed to wait_for_owner_exiting().\n\n  CPU0\t\t\t     CPU1\t\t       CPU2\n  futex_lock_pi(uaddr)\n  // acquires the PI futex\n  exit()\n    futex_cleanup_begin()\n      futex_state = EXITING;\n\t\t\t     futex_lock_pi(uaddr)\n\t\t\t       futex_lock_pi_atomic()\n\t\t\t\t attach_to_pi_owner()\n\t\t\t\t   // observes EXITING\n\t\t\t\t   *exiting = owner;  // takes ref\n\t\t\t\t   return -EBUSY\n\t\t\t       wait_for_owner_exiting(-EBUSY, owner)\n\t\t\t\t put_task_struct();   // drops ref\n\t\t\t       // exiting still points to owner\n\t\t\t       goto retry;\n\t\t\t       futex_lock_pi_atomic()\n\t\t\t\t lock_pi_update_atomic()\n\t\t\t\t   cmpxchg(uaddr)\n\t\t\t\t\t*uaddr ^= WAITERS // whatever\n\t\t\t\t   // value changed\n\t\t\t\t return -EAGAIN;\n\t\t\t       wait_for_owner_exiting(-EAGAIN, exiting) // stale\n\t\t\t\t WARN_ON_ONCE(exiting)\n\nFix this by resetting upon retry, essentially aligning it with requeue_pi."
          }
        ],
        "id": "CVE-2026-31555",
        "lastModified": "2026-07-14T13:18:45.463",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 5.5,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.8,
              "impactScore": 3.6,
              "source": "nvd@nist.gov",
              "type": "Primary"
            }
          ]
        },
        "published": "2026-04-24T15:16:29.837",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/210d36d892de5195e6766c45519dfb1e65f3eb83"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/33095ae3bdde5e5c264d7e88a2f3e7703a26c7aa"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/5e8e06bf8909e79b4acd950cf578cfc2f10bbefa"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/71112e62807d1925dc3ae6188b11f8cfc85aec23"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/7475dfad10a05a5bfadebf5f2499bd61b19ed293"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/92e47ad03e03dbb5515bdf06444bf6b1e147310d"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/de7c0c04ad868f2cee6671b11c0a6d20421af1da"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/e7824ec168d2ac883a213cd1f4d6cc0816002a85"
          },
          {
            "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
          },
          {
            "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "NVD-CWE-noinfo"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-15T23:44:33+00:00",
      "cve": "CVE-2026-31555",
      "id": "CVE-2026-31555",
      "initial_release_date": "2026-04-24T00:00:00+00:00",
      "product_status:fixed": "303",
      "product_status:known_affected": "174",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: futex: Clear stale exiting pointer in futex_lock_pi() retry path",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31555.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-11T01:30:49Z",
      "cve": "CVE-2026-31555",
      "id": "CVE-2026-31555",
      "initial_release_date": "2026-04-25T01:39:34Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "530",
      "product_status:known_not_affected": "180",
      "product_status:recommended": "279",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-31555",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-31555.json",
      "version": "24"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.