GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2025-21946 (GCVE-0-2025-21946)

Vulnerability from cvelistv5 – Published: 2025-04-01 15:41 – Updated: 2026-08-05 11:55
VLAI
Title
ksmbd: fix out-of-bounds in parse_sec_desc()
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds in parse_sec_desc() If osidoffset, gsidoffset and dacloffset could be greater than smb_ntsd struct size. If it is smaller, It could cause slab-out-of-bounds. And when validating sid, It need to check it included subauth array size.
Severity
8.8 (High)
CVSS:3.1/AV:N/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: 0626e6641f6b467447c81dd7678a69c66f7746cf , < f4ee19528664777af8b842f8f001be98345aa973 (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < c1569dbbe2d43041be9f3fef7ca08bec3b66ad1b (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 159d059cbcb0e6d0e7a7b34af3862ba09a6b22d1 (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 6a9831180d0b23b5c97e2bd841aefc8f82900172 (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < d6e13e19063db24f94b690159d0633aaf72a0f03 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 6.1.160 , ≤ 6.1.* (semver)
Unaffected: 6.6.83 , ≤ 6.6.* (semver)
Unaffected: 6.12.19 , ≤ 6.12.* (semver)
Unaffected: 6.13.7 , ≤ 6.13.* (semver)
Unaffected: 6.14 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smbacl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f4ee19528664777af8b842f8f001be98345aa973",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            },
            {
              "lessThan": "c1569dbbe2d43041be9f3fef7ca08bec3b66ad1b",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            },
            {
              "lessThan": "159d059cbcb0e6d0e7a7b34af3862ba09a6b22d1",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            },
            {
              "lessThan": "6a9831180d0b23b5c97e2bd841aefc8f82900172",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            },
            {
              "lessThan": "d6e13e19063db24f94b690159d0633aaf72a0f03",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smbacl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.83",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.19",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.13.*",
              "status": "unaffected",
              "version": "6.13.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.14",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.160",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.83",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.19",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.13.7",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.14",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix out-of-bounds in parse_sec_desc()\n\nIf osidoffset, gsidoffset and dacloffset could be greater than smb_ntsd\nstruct size. If it is smaller, It could cause slab-out-of-bounds.\nAnd when validating sid, It need to check it included subauth array size."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - ksmbd is the in-kernel SMB server listening on TCP/445, and every field driving the bug (osidoffset/gsidoffset/dacloffset, num_subauth, BufferLength) comes directly from a remote client\u0027s SMB2_SET_INFO or SMB2_CREATE PDU. No local access is required.\nAC:L - The attacker fully controls the security-descriptor offsets, num_subauth, and the total PDU size, so the out-of-bounds access is deterministic on every request; no race, timing window, or uncontrollable memory-layout condition is involved.\nPR:L - The path requires an established SMB session and a tree connect with KSMBD_TREE_CONN_FLAG_WRITABLE plus an open file handle, so a low-privileged share user (or a guest account where \"map to guest\" is configured) suffices \u2014 no administrative rights on the target.\nUI:N - The attacker drives the entire sequence (negotiate, session setup, tree connect, create, set-info) from its own client; no action by any local user or administrator is needed.\nS:U - The out-of-bounds access occurs in the ksmbd kernel thread and its consequences stay within the kernel\u0027s own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The read runs up to ~60 bytes past the request buffer at an attacker-chosen offset, and the leaked 32-bit word is written into the file\u0027s owner uid/gid and read straight back via SMB2_QUERY_INFO security, producing a repeatable remote heap-disclosure oracle (compare_sids() on the owner SID gives a second oracle) that can be aimed at sprayed adjacent objects containing pointers or other clients\u0027 data.\nI:H - Out-of-bounds kernel memory directly determines security-relevant persistent state \u2014 notify_change() sets the file\u0027s owner uid/gid and set_posix_acl()/mode are derived from the same unvalidated SID data \u2014 so the attacker causes modification of filesystem ownership and permission metadata from memory outside the intended object.\nA:H - With ~4 MB PDUs the request buffer is vmalloc-backed, and the attacker can size it so the allocation ends exactly on a page boundary, making the sub_auth[] read hit the vmalloc guard page and oops the ksmbd kernel thread; on KASAN/hardened builds the slab-out-of-bounds report panics the machine outright."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:55:31.476Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f4ee19528664777af8b842f8f001be98345aa973"
        },
        {
          "url": "https://git.kernel.org/stable/c/c1569dbbe2d43041be9f3fef7ca08bec3b66ad1b"
        },
        {
          "url": "https://git.kernel.org/stable/c/159d059cbcb0e6d0e7a7b34af3862ba09a6b22d1"
        },
        {
          "url": "https://git.kernel.org/stable/c/6a9831180d0b23b5c97e2bd841aefc8f82900172"
        },
        {
          "url": "https://git.kernel.org/stable/c/d6e13e19063db24f94b690159d0633aaf72a0f03"
        }
      ],
      "title": "ksmbd: fix out-of-bounds in parse_sec_desc()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-21946",
    "datePublished": "2025-04-01T15:41:08.955Z",
    "dateReserved": "2024-12-29T08:45:45.790Z",
    "dateUpdated": "2026-08-05T11:55:31.476Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-21946",
      "date": "2026-09-18",
      "epss": "0.00483",
      "percentile": "0.40688"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "fs/smb/server/smbacl.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "f4ee19528664777af8b842f8f001be98345aa973",
                    "status": "affected",
                    "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "c1569dbbe2d43041be9f3fef7ca08bec3b66ad1b",
                    "status": "affected",
                    "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "159d059cbcb0e6d0e7a7b34af3862ba09a6b22d1",
                    "status": "affected",
                    "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "6a9831180d0b23b5c97e2bd841aefc8f82900172",
                    "status": "affected",
                    "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "d6e13e19063db24f94b690159d0633aaf72a0f03",
                    "status": "affected",
                    "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
                    "versionType": "git"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "fs/smb/server/smbacl.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "5.15"
                  },
                  {
                    "lessThan": "5.15",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.1.*",
                    "status": "unaffected",
                    "version": "6.1.160",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.6.*",
                    "status": "unaffected",
                    "version": "6.6.83",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.12.*",
                    "status": "unaffected",
                    "version": "6.12.19",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.13.*",
                    "status": "unaffected",
                    "version": "6.13.7",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "6.14",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "73798B7D-CA2B-49C7-B28D-CFF283BB6A39",
                    "versionEndExcluding": "6.6.83",
                    "versionStartIncluding": "5.15",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "32865E5C-8AE1-4D3D-A64D-299039694A88",
                    "versionEndExcluding": "6.12.19",
                    "versionStartIncluding": "6.7",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "842F5A44-3E71-4546-B4FD-43B0ACE3F32B",
                    "versionEndExcluding": "6.13.7",
                    "versionStartIncluding": "6.13",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*",
                    "matchCriteriaId": "186716B6-2B66-4BD0-852E-D48E71C0C85F",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*",
                    "matchCriteriaId": "0D3E781C-403A-498F-9DA9-ECEE50F41E75",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*",
                    "matchCriteriaId": "66619FB8-0AAF-4166-B2CF-67B24143261D",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:*",
                    "matchCriteriaId": "D3D6550E-6679-4560-902D-AF52DCFE905B",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc5:*:*:*:*:*:*",
                    "matchCriteriaId": "45B90F6B-BEC7-4D4E-883A-9DBADE021750",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix out-of-bounds in parse_sec_desc()\n\nIf osidoffset, gsidoffset and dacloffset could be greater than smb_ntsd\nstruct size. If it is smaller, It could cause slab-out-of-bounds.\nAnd when validating sid, It need to check it included subauth array size."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ksmbd: se corrige un error fuera de los l\u00edmites en parse_sec_desc(). Si osidoffset, gsidoffset y dacloffset pueden ser mayores que el tama\u00f1o de la estructura smb_ntsd, si es menor, podr\u00eda causar un error fuera de los l\u00edmites de slab. Al validar sid, es necesario comprobar si incluye el tama\u00f1o del array subauth."
          }
        ],
        "id": "CVE-2025-21946",
        "lastModified": "2026-07-30T06:21:58.743",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 8.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            },
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.1,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.8,
              "impactScore": 5.2,
              "source": "nvd@nist.gov",
              "type": "Primary"
            }
          ]
        },
        "published": "2025-04-01T16:15:25.730",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/159d059cbcb0e6d0e7a7b34af3862ba09a6b22d1"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/6a9831180d0b23b5c97e2bd841aefc8f82900172"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/c1569dbbe2d43041be9f3fef7ca08bec3b66ad1b"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/d6e13e19063db24f94b690159d0633aaf72a0f03"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/f4ee19528664777af8b842f8f001be98345aa973"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-125"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-30T10:19:03+00:00",
      "cve": "CVE-2025-21946",
      "id": "CVE-2025-21946",
      "initial_release_date": "2025-04-01T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ksmbd: fix out-of-bounds in parse_sec_desc()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-21946.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-29T01:26:17Z",
      "cve": "CVE-2025-21946",
      "id": "CVE-2025-21946",
      "initial_release_date": "2025-04-04T02:58:51Z",
      "product_status:known_not_affected": "560",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-21946",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-21946.json",
      "version": "10"
    }
  }
}



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.


Detection rules are retrieved from Rulezet.


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.