CVE-2026-52933 (GCVE-0-2026-52933)

Vulnerability from cvelistv5 – Published: 2026-06-24 07:14 – Updated: 2026-09-08 08:49
VLAI
Title
io_uring/poll: fix signed comparison in io_poll_get_ownership()
Summary
In the Linux kernel, the following vulnerability has been resolved: io_uring/poll: fix signed comparison in io_poll_get_ownership() io_poll_get_ownership() uses a signed comparison to check whether poll_refs has reached the threshold for the slowpath: if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS)) atomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG (BIT(31)) is set in poll_refs, the value becomes negative in signed arithmetic, so the >= 128 comparison always evaluates to false and the slowpath is never taken. Fix this by casting the atomic_read() result to unsigned int before the comparison, so that the cancel flag is treated as a large positive value and correctly triggers the slowpath.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a26a35e9019fd70bf3cf647dcfdae87abc7bacea , < 81bf96b0abbfa4cd47ea32e12596aed3855fb2f3 (git)
Affected: a26a35e9019fd70bf3cf647dcfdae87abc7bacea , < cf522703d4f194991615763697ae25a3f9539763 (git)
Affected: a26a35e9019fd70bf3cf647dcfdae87abc7bacea , < fc47043f3d9af3efa407665b47f8378ec691ba18 (git)
Affected: a26a35e9019fd70bf3cf647dcfdae87abc7bacea , < ea0697129807d718037f618221037aa0660ee3c5 (git)
Affected: a26a35e9019fd70bf3cf647dcfdae87abc7bacea , < c6d191164dc81838d8dbf452a6000f68c558d1ae (git)
Affected: a26a35e9019fd70bf3cf647dcfdae87abc7bacea , < 326941b22806cbf2df1fbfe902b7908b368cce42 (git)
Affected: 4b702b7d11ce1b9d26fc6d7c5a7ef4ac1d455048 (git)
Affected: bc4e6ee16778149811333a969a7a893d4cc110c5 (git)
Affected: 5.15.82 , < 5.16 (semver)
Affected: 6.0.11 , < 6.1 (semver)
guessed Create a notification for this product.
Linux Linux Affected: 6.1
Unaffected: 0 , < 6.1 (semver)
Unaffected: 6.1.175 , ≤ 6.1.* (semver)
Unaffected: 6.6.140 , ≤ 6.6.* (semver)
Unaffected: 6.12.86 , ≤ 6.12.* (semver)
Unaffected: 6.18.27 , ≤ 6.18.* (semver)
Unaffected: 7.0.4 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (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 1518F-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: V3.1.6 , < * (custom)
guessed Create a notification for this product.
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                    "matchCriteriaId": "A1A92866-F406-43B5-B2D1-CFC274753E9D",
                    "versionEndExcluding": "6.6.140",
                    "versionStartIncluding": "6.2",
                    "vulnerable": true
                  },
                  {
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                    "matchCriteriaId": "55DA1C62-9991-451E-B8A8-E0004E00F789",
                    "versionEndExcluding": "6.12.86",
                    "versionStartIncluding": "6.7",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "A10AC84F-C058-47D5-85B4-E6E51A613B74",
                    "versionEndExcluding": "6.18.27",
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                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "CDB78D6D-22C3-4154-B0D0-94AF1CE5C2E3",
                    "versionEndExcluding": "7.0.4",
                    "versionStartIncluding": "6.19",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.1:-:*:*:*:*:*:*",
                    "matchCriteriaId": "DE093B34-F4CD-4052-8122-730D6537A91A",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.1:rc7:*:*:*:*:*:*",
                    "matchCriteriaId": "8535320E-A0DB-4277-800E-D0CE5BBA59E8",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.1:rc8:*:*:*:*:*:*",
                    "matchCriteriaId": "21718AA4-4056-40F2-968E-BDAA465A7872",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/poll: fix signed comparison in io_poll_get_ownership()\n\nio_poll_get_ownership() uses a signed comparison to check whether\npoll_refs has reached the threshold for the slowpath:\n\n    if (unlikely(atomic_read(\u0026req-\u003epoll_refs) \u003e= IO_POLL_REF_BIAS))\n\natomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG\n(BIT(31)) is set in poll_refs, the value becomes negative in\nsigned arithmetic, so the \u003e= 128 comparison always evaluates to\nfalse and the slowpath is never taken.\n\nFix this by casting the atomic_read() result to unsigned int\nbefore the comparison, so that the cancel flag is treated as a\nlarge positive value and correctly triggers the slowpath."
          }
        ],
        "id": "CVE-2026-52933",
        "lastModified": "2026-09-08T09:18:11.540",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.8,
              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-06-24T08:16:23.480",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/326941b22806cbf2df1fbfe902b7908b368cce42"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
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            "url": "https://git.kernel.org/stable/c/81bf96b0abbfa4cd47ea32e12596aed3855fb2f3"
          },
          {
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            "tags": [
              "Patch"
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            "url": "https://git.kernel.org/stable/c/c6d191164dc81838d8dbf452a6000f68c558d1ae"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
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            "url": "https://git.kernel.org/stable/c/cf522703d4f194991615763697ae25a3f9539763"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/ea0697129807d718037f618221037aa0660ee3c5"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/fc47043f3d9af3efa407665b47f8378ec691ba18"
          },
          {
            "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-835"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-16T15:29:18+00:00",
      "cve": "CVE-2026-52933",
      "id": "CVE-2026-52933",
      "initial_release_date": "2026-06-24T00:00:00+00:00",
      "product_status:fixed": "1457",
      "product_status:known_affected": "22",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: io_uring/poll: fix signed comparison in io_poll_get_ownership()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52933.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-19T01:54:45Z",
      "cve": "CVE-2026-52933",
      "id": "CVE-2026-52933",
      "initial_release_date": "2026-06-25T02:19:50Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "398",
      "product_status:known_not_affected": "221",
      "product_status:recommended": "432",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-52933",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-52933.json",
      "version": "21"
    }
  }
}



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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

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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.