CVE-2026-99040 (GCVE-0-2026-99040)

Vulnerability from cvelistv5 – Published: 2026-10-23 12:21 – Updated: 2026-10-23 12:21
VLAI
Title
KEYS: Fix add_key() race with keyring restriction
Summary
In the Linux kernel, the following vulnerability has been resolved: KEYS: Fix add_key() race with keyring restriction __key_create_or_update() snapshots keyring->restrict_link before taking the destination keyring's semaphore. keyring_restrict() installs a restriction while holding that semaphore. This allows a writer to observe no restriction, wait for the keyring owner to install a reject-all restriction and return successfully, and then link a key using the stale NULL snapshot. The writer only needs write permission on the destination keyring. Move the restrict_link read after __key_link_lock() and __key_link_begin(). The read and the subsequent restriction check are then serialized with restriction installation by keyring->sem. The race was reproduced on v7.2.8 in 19 executions where restriction installation returned before the link completed. All 19 linked the key despite the reject-all restriction. With this change, 312 executions reached the same ordering and every add_key() call failed with -EPERM. The issue was found by manual concurrency analysis assisted by AI-based analysis and independently verified with a QEMU reproducer and kernel instrumentation.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7056 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c , < 305f1828b871dd46bf41addeb6f11d2c162dcb25 (git)
Affected: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c , < f99399b48e3edd6851fac34cd329bab9f1f33baf (git)
Affected: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c , < 11516a0c402a6c1fa52254aa70d8d65fb921e59e (git)
Affected: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c , < da0b595d8e6e2dd798f6e34e09dc51a13b888514 (git)
Affected: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c , < dd3ea3fcba7c75493760cdbccd35f029597e8d5e (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.7
Unaffected: 0 , < 4.7 (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.113 , ≤ 6.12.* (semver)
Unaffected: 6.18.57 , ≤ 6.18.* (semver)
Unaffected: 7.2.11 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (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": [
            "security/keys/key.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "305f1828b871dd46bf41addeb6f11d2c162dcb25",
              "status": "affected",
              "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
              "versionType": "git"
            },
            {
              "lessThan": "f99399b48e3edd6851fac34cd329bab9f1f33baf",
              "status": "affected",
              "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
              "versionType": "git"
            },
            {
              "lessThan": "11516a0c402a6c1fa52254aa70d8d65fb921e59e",
              "status": "affected",
              "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
              "versionType": "git"
            },
            {
              "lessThan": "da0b595d8e6e2dd798f6e34e09dc51a13b888514",
              "status": "affected",
              "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
              "versionType": "git"
            },
            {
              "lessThan": "dd3ea3fcba7c75493760cdbccd35f029597e8d5e",
              "status": "affected",
              "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "security/keys/key.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.7"
            },
            {
              "lessThan": "4.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.113",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.57",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.113",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.57",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.11",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKEYS: Fix add_key() race with keyring restriction\n\n__key_create_or_update() snapshots keyring-\u003erestrict_link before taking\nthe destination keyring\u0027s semaphore.  keyring_restrict() installs a\nrestriction while holding that semaphore.\n\nThis allows a writer to observe no restriction, wait for the keyring\nowner to install a reject-all restriction and return successfully, and\nthen link a key using the stale NULL snapshot.  The writer only needs\nwrite permission on the destination keyring.\n\nMove the restrict_link read after __key_link_lock() and\n__key_link_begin().  The read and the subsequent restriction check are\nthen serialized with restriction installation by keyring-\u003esem.\n\nThe race was reproduced on v7.2.8 in 19 executions where restriction\ninstallation returned before the link completed.  All 19 linked the key\ndespite the reject-all restriction.  With this change, 312 executions\nreached the same ordering and every add_key() call failed with -EPERM.\n\nThe issue was found by manual concurrency analysis assisted by AI-based\nanalysis and independently verified with a QEMU reproducer and kernel\ninstrumentation."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-23T12:21:59.288Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/305f1828b871dd46bf41addeb6f11d2c162dcb25"
        },
        {
          "url": "https://git.kernel.org/stable/c/f99399b48e3edd6851fac34cd329bab9f1f33baf"
        },
        {
          "url": "https://git.kernel.org/stable/c/11516a0c402a6c1fa52254aa70d8d65fb921e59e"
        },
        {
          "url": "https://git.kernel.org/stable/c/da0b595d8e6e2dd798f6e34e09dc51a13b888514"
        },
        {
          "url": "https://git.kernel.org/stable/c/dd3ea3fcba7c75493760cdbccd35f029597e8d5e"
        }
      ],
      "title": "KEYS: Fix add_key() race with keyring restriction",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99040",
    "datePublished": "2026-10-23T12:21:59.288Z",
    "dateReserved": "2026-09-25T10:25:14.387Z",
    "dateUpdated": "2026-10-23T12:21:59.288Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-99040",
      "date": "2026-10-25",
      "epss": "0.00181",
      "percentile": "0.07629"
    },
    "microsoft_vex": {
      "current_release_date": "2026-10-25T01:05:22.000Z",
      "cve": "CVE-2026-99040",
      "id": "msrc_CVE-2026-99040",
      "initial_release_date": "2026-10-25T01:04:21.000Z",
      "product_status:under_investigation": "2",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "KEYS: Fix add_key() race with keyring restriction",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-99040.json",
      "version": "2"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "security/keys/key.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "305f1828b871dd46bf41addeb6f11d2c162dcb25",
                    "status": "affected",
                    "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "f99399b48e3edd6851fac34cd329bab9f1f33baf",
                    "status": "affected",
                    "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "11516a0c402a6c1fa52254aa70d8d65fb921e59e",
                    "status": "affected",
                    "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "da0b595d8e6e2dd798f6e34e09dc51a13b888514",
                    "status": "affected",
                    "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "dd3ea3fcba7c75493760cdbccd35f029597e8d5e",
                    "status": "affected",
                    "version": "5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c",
                    "versionType": "git"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "security/keys/key.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "4.7"
                  },
                  {
                    "lessThan": "4.7",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.6.*",
                    "status": "unaffected",
                    "version": "6.6.160",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.12.*",
                    "status": "unaffected",
                    "version": "6.12.113",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.18.*",
                    "status": "unaffected",
                    "version": "6.18.57",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "7.2.*",
                    "status": "unaffected",
                    "version": "7.2.11",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.3",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKEYS: Fix add_key() race with keyring restriction\n\n__key_create_or_update() snapshots keyring-\u003erestrict_link before taking\nthe destination keyring\u0027s semaphore.  keyring_restrict() installs a\nrestriction while holding that semaphore.\n\nThis allows a writer to observe no restriction, wait for the keyring\nowner to install a reject-all restriction and return successfully, and\nthen link a key using the stale NULL snapshot.  The writer only needs\nwrite permission on the destination keyring.\n\nMove the restrict_link read after __key_link_lock() and\n__key_link_begin().  The read and the subsequent restriction check are\nthen serialized with restriction installation by keyring-\u003esem.\n\nThe race was reproduced on v7.2.8 in 19 executions where restriction\ninstallation returned before the link completed.  All 19 linked the key\ndespite the reject-all restriction.  With this change, 312 executions\nreached the same ordering and every add_key() call failed with -EPERM.\n\nThe issue was found by manual concurrency analysis assisted by AI-based\nanalysis and independently verified with a QEMU reproducer and kernel\ninstrumentation."
          }
        ],
        "id": "CVE-2026-99040",
        "lastModified": "2026-10-23T13:17:27.360",
        "metrics": {},
        "published": "2026-10-23T13:17:27.360",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/11516a0c402a6c1fa52254aa70d8d65fb921e59e"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/305f1828b871dd46bf41addeb6f11d2c162dcb25"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/da0b595d8e6e2dd798f6e34e09dc51a13b888514"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/dd3ea3fcba7c75493760cdbccd35f029597e8d5e"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/f99399b48e3edd6851fac34cd329bab9f1f33baf"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    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.