CVE-2025-39931 (GCVE-0-2025-39931)

Vulnerability from cvelistv5 – Published: 2025-10-04 07:30 – Updated: 2026-09-08 08:42
VLAI
Title
crypto: af_alg - Set merge to zero early in af_alg_sendmsg
Summary
In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Set merge to zero early in af_alg_sendmsg If an error causes af_alg_sendmsg to abort, ctx->merge may contain a garbage value from the previous loop. This may then trigger a crash on the next entry into af_alg_sendmsg when it attempts to do a merge that can't be done. Fix this by setting ctx->merge to zero near the start of the loop.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 54/100 over 6618 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < db2b42425dfbde4983b0c20fb7cfa05f70e6a745 (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 6241b9e2809b12da9130894cf5beddf088dc1b8a (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 2374c11189ef704a3e4863646369f1b8e6a27d71 (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 24c1106504c625fabd3b7229611af617b4c27ac7 (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 045ee26aa3920a47ec46d7fcb302420bf01fd753 (git)
Affected: 8ff590903d5fc7f5a0a988c38267a3d08e6393a2 , < 9574b2330dbd2b5459b74d3b5e9619d39299fc6f (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.38
Unaffected: 0 , < 2.6.38 (semver)
Unaffected: 5.10.260 , ≤ 5.10.* (semver)
Unaffected: 5.15.211 , ≤ 5.15.* (semver)
Unaffected: 6.1.154 , ≤ 6.1.* (semver)
Unaffected: 6.6.108 , ≤ 6.6.* (semver)
Unaffected: 6.12.49 , ≤ 6.12.* (semver)
Unaffected: 6.16.9 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
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 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: V3.1.5 , < * (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 SIPLUS S7-1500 CPU 1518-4 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.
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": "V3.1.5",
                "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 1518-4 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": "SIMATIC S7-1500 CPU 1518F-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"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-08T08:42:33.347Z",
          "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": [
            "crypto/af_alg.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf",
              "status": "affected",
              "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
              "versionType": "git"
            },
            {
              "lessThan": "db2b42425dfbde4983b0c20fb7cfa05f70e6a745",
              "status": "affected",
              "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
              "versionType": "git"
            },
            {
              "lessThan": "6241b9e2809b12da9130894cf5beddf088dc1b8a",
              "status": "affected",
              "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
              "versionType": "git"
            },
            {
              "lessThan": "2374c11189ef704a3e4863646369f1b8e6a27d71",
              "status": "affected",
              "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
              "versionType": "git"
            },
            {
              "lessThan": "24c1106504c625fabd3b7229611af617b4c27ac7",
              "status": "affected",
              "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
              "versionType": "git"
            },
            {
              "lessThan": "045ee26aa3920a47ec46d7fcb302420bf01fd753",
              "status": "affected",
              "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
              "versionType": "git"
            },
            {
              "lessThan": "9574b2330dbd2b5459b74d3b5e9619d39299fc6f",
              "status": "affected",
              "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "crypto/af_alg.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.38"
            },
            {
              "lessThan": "2.6.38",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.260",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.211",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.154",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.108",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.49",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.260",
                  "versionStartIncluding": "2.6.38",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.211",
                  "versionStartIncluding": "2.6.38",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.154",
                  "versionStartIncluding": "2.6.38",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.108",
                  "versionStartIncluding": "2.6.38",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.49",
                  "versionStartIncluding": "2.6.38",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16.9",
                  "versionStartIncluding": "2.6.38",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17",
                  "versionStartIncluding": "2.6.38",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: af_alg - Set merge to zero early in af_alg_sendmsg\n\nIf an error causes af_alg_sendmsg to abort, ctx-\u003emerge may contain\na garbage value from the previous loop.  This may then trigger a\ncrash on the next entry into af_alg_sendmsg when it attempts to do\na merge that can\u0027t be done.\n\nFix this by setting ctx-\u003emerge to zero near the start of the loop."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - AF_ALG is a local kernel-crypto socket interface reached via socket()/bind()/sendmsg() syscalls; there is no network exposure. Exploitation requires a local account to issue the syscalls.\nAC:L - The attacker controls both the error-aborting sendmsg (a fault in memcpy_from_msg or a forced allocation error is trivially induced) and the subsequent merge-triggering sendmsg, so the condition is reliably created; heap grooming for full exploitation is also within attacker control.\nPR:L - Creating and driving an AF_ALG socket requires no capabilities and passes no privilege check, so any basic unprivileged local user can reach the vulnerable path.\nUI:N - The entire sequence is performed by the attacker\u0027s own process with no victim action required.\nS:U - The corruption stays within the kernel\u0027s own security authority (standard local privilege escalation); no VM/IOMMU/sandbox boundary is crossed.\nC:H - The stale merge flag causes an out-of-bounds scatterlist read and a heap write primitive that can be leveraged to disclose kernel memory contents.\nI:H - The merge path performs an attacker-controlled write to an address derived from an out-of-bounds-read scatterlist entry, giving a heap out-of-bounds write suitable for control-flow hijacking/privilege escalation.\nA:H - The inconsistent tsgl state and wild write reliably cause kernel memory corruption and panic/oops."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:06:10.490Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf"
        },
        {
          "url": "https://git.kernel.org/stable/c/db2b42425dfbde4983b0c20fb7cfa05f70e6a745"
        },
        {
          "url": "https://git.kernel.org/stable/c/6241b9e2809b12da9130894cf5beddf088dc1b8a"
        },
        {
          "url": "https://git.kernel.org/stable/c/2374c11189ef704a3e4863646369f1b8e6a27d71"
        },
        {
          "url": "https://git.kernel.org/stable/c/24c1106504c625fabd3b7229611af617b4c27ac7"
        },
        {
          "url": "https://git.kernel.org/stable/c/045ee26aa3920a47ec46d7fcb302420bf01fd753"
        },
        {
          "url": "https://git.kernel.org/stable/c/9574b2330dbd2b5459b74d3b5e9619d39299fc6f"
        }
      ],
      "title": "crypto: af_alg - Set merge to zero early in af_alg_sendmsg",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39931",
    "datePublished": "2025-10-04T07:30:55.964Z",
    "dateReserved": "2025-04-16T07:20:57.147Z",
    "dateUpdated": "2026-09-08T08:42:33.347Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-39931",
      "date": "2026-10-10",
      "epss": "0.00161",
      "percentile": "0.04772"
    },
    "microsoft_vex": {
      "current_release_date": "2025-10-05T01:03:19.000Z",
      "cve": "CVE-2025-39931",
      "id": "msrc_CVE-2025-39931",
      "initial_release_date": "2025-10-02T00:00:00.000Z",
      "product_status:fixed": "1",
      "product_status:known_affected": "2",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "crypto: af_alg - Set merge to zero early in af_alg_sendmsg",
      "url": "https://msrc.microsoft.com/csaf/vex/2025/msrc_cve-2025-39931.json",
      "version": "1"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "crypto/af_alg.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf",
                    "status": "affected",
                    "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "db2b42425dfbde4983b0c20fb7cfa05f70e6a745",
                    "status": "affected",
                    "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "6241b9e2809b12da9130894cf5beddf088dc1b8a",
                    "status": "affected",
                    "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "2374c11189ef704a3e4863646369f1b8e6a27d71",
                    "status": "affected",
                    "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "24c1106504c625fabd3b7229611af617b4c27ac7",
                    "status": "affected",
                    "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "045ee26aa3920a47ec46d7fcb302420bf01fd753",
                    "status": "affected",
                    "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "9574b2330dbd2b5459b74d3b5e9619d39299fc6f",
                    "status": "affected",
                    "version": "8ff590903d5fc7f5a0a988c38267a3d08e6393a2",
                    "versionType": "git"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "crypto/af_alg.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "2.6.38"
                  },
                  {
                    "lessThan": "2.6.38",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "5.10.*",
                    "status": "unaffected",
                    "version": "5.10.260",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "5.15.*",
                    "status": "unaffected",
                    "version": "5.15.211",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.1.*",
                    "status": "unaffected",
                    "version": "6.1.154",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.6.*",
                    "status": "unaffected",
                    "version": "6.6.108",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.12.*",
                    "status": "unaffected",
                    "version": "6.12.49",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.16.*",
                    "status": "unaffected",
                    "version": "6.16.9",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "6.17",
                    "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": "V3.1.5",
                    "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 1518-4 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": "SIMATIC S7-1500 CPU 1518F-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"
                  }
                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.6",
                    "versionType": "custom"
                  }
                ]
              }
            ],
            "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "90C36693-745D-4EC3-A247-5887CAEA12C7",
                    "versionEndExcluding": "6.1.154",
                    "versionStartIncluding": "2.6.38",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "A7E8EAEE-7731-4996-9578-696255D61EA2",
                    "versionEndExcluding": "6.6.108",
                    "versionStartIncluding": "6.2",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "CAA033E9-A2C5-4976-A83E-9804D8FB827F",
                    "versionEndExcluding": "6.12.49",
                    "versionStartIncluding": "6.7",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "638DD910-1189-4F5E-98BF-2D436B695112",
                    "versionEndExcluding": "6.16.9",
                    "versionStartIncluding": "6.13",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*",
                    "matchCriteriaId": "327D22EF-390B-454C-BD31-2ED23C998A1C",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*",
                    "matchCriteriaId": "C730CD9A-D969-4A8E-9522-162AAF7C0EE9",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*",
                    "matchCriteriaId": "39982C4B-716E-4B2F-8196-FA301F47807D",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*",
                    "matchCriteriaId": "340BEEA9-D70D-4290-B502-FBB1032353B1",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:*",
                    "matchCriteriaId": "47E4C5C0-079F-4838-971B-8C503D48FCC2",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc6:*:*:*:*:*:*",
                    "matchCriteriaId": "5A4516A6-C12E-42A4-8C0E-68AEF3264504",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: af_alg - Set merge to zero early in af_alg_sendmsg\n\nIf an error causes af_alg_sendmsg to abort, ctx-\u003emerge may contain\na garbage value from the previous loop.  This may then trigger a\ncrash on the next entry into af_alg_sendmsg when it attempts to do\na merge that can\u0027t be done.\n\nFix this by setting ctx-\u003emerge to zero near the start of the loop."
          }
        ],
        "id": "CVE-2025-39931",
        "lastModified": "2026-07-30T06:23:58.207",
        "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"
            },
            {
              "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": "2025-10-04T08:15:45.827",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/045ee26aa3920a47ec46d7fcb302420bf01fd753"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/2374c11189ef704a3e4863646369f1b8e6a27d71"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/24c1106504c625fabd3b7229611af617b4c27ac7"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/6241b9e2809b12da9130894cf5beddf088dc1b8a"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/9574b2330dbd2b5459b74d3b5e9619d39299fc6f"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/db2b42425dfbde4983b0c20fb7cfa05f70e6a745"
          },
          {
            "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": "CWE-908"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-30T08:53:41+00:00",
      "cve": "CVE-2025-39931",
      "id": "CVE-2025-39931",
      "initial_release_date": "2025-10-04T00:00:00+00:00",
      "product_status:known_affected": "260",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: crypto: af_alg - Set merge to zero early in af_alg_sendmsg",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39931.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-10-01T01:39:48Z",
      "cve": "CVE-2025-39931",
      "id": "CVE-2025-39931",
      "initial_release_date": "2025-10-05T02:52:39Z",
      "product_status:known_affected": "731",
      "product_status:recommended": "501",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-39931",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-39931.json",
      "version": "56"
    }
  }
}



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.