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GHSA-WJ9X-QHWH-XF9H

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-14 00:31

Details

In the Linux kernel, the following vulnerability has been resolved:

fs: preserve ACL_DONT_CACHE state in forget_cached_acl()

The ACL_DONT_CACHE state is meant to be a constant state for the inode for filesystems that want to opt out of posix acl caching.

Commit facd61053cff1 ("fuse: fixes after adapting to new posix acl api") used this facility to opt out of posix acl caching for fuse inodes with fuse server that does not negotiate FUSE_POSIX_ACL (fc->posix_acl).

The commit also takes care to gate the forget_all_cached_acls() call in fuse_set_acl() on fc->posix_acl because there is no need for it, but there are other placed in fuse code which call forget_all_cached_acls() unconditional to fc->posix_acl and those cause the loss of the ACL_DONT_CACHE state.

This is not only a functional bug. Properly timed, a get_acl() from this fuse filesystem can return a stale cached value, as was observed in tests, because set_acl() does not invalidate the unintentional acl cache.

We could fix this in fuse, but it actually makes no sense for the vfs helper forget_cached_acl() to invalidate the ACL_DONT_CACHE state, so let it not do that to fix fuse and future users of ACL_DONT_CACHE.

Severity

8.4 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-68149"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:20:00Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs: preserve ACL_DONT_CACHE state in forget_cached_acl()\n\nThe ACL_DONT_CACHE state is meant to be a constant state for the inode\nfor filesystems that want to opt out of posix acl caching.\n\nCommit facd61053cff1 (\"fuse: fixes after adapting to new posix acl api\")\nused this facility to opt out of posix acl caching for fuse inodes with\nfuse server that does not negotiate FUSE_POSIX_ACL (fc-\u003eposix_acl).\n\nThe commit also takes care to gate the forget_all_cached_acls() call in\nfuse_set_acl() on fc-\u003eposix_acl because there is no need for it, but\nthere are other placed in fuse code which call forget_all_cached_acls()\nunconditional to fc-\u003eposix_acl and those cause the loss of the\nACL_DONT_CACHE state.\n\nThis is not only a functional bug. Properly timed, a get_acl() from this\nfuse filesystem can return a stale cached value, as was observed in tests,\nbecause set_acl() does not invalidate the unintentional acl cache.\n\nWe could fix this in fuse, but it actually makes no sense for the vfs\nhelper forget_cached_acl() to invalidate the ACL_DONT_CACHE state, so\nlet it not do that to fix fuse and future users of ACL_DONT_CACHE.",
  "id": "GHSA-wj9x-qhwh-xf9h",
  "modified": "2026-08-14T00:31:52Z",
  "published": "2026-08-10T15:33:38Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68149"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4b9a5458d02e214ef2b384124ca626e3e381d778"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/834ddf899484a2f23129080e8773bc04f4691d07"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a019b074903b3ad0a9726087efd0e8291452023b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b98fad81f1202b0eb26aacf3ff4cc7a21ed3b5bf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ca03a7984a34f48085fd013e0d2cf4e6420b4acf"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-68149 (GCVE-0-2026-68149)

Vulnerability from cvelistv5 – Published: 2026-08-10 11:59 – Updated: 2026-08-17 04:59

Title

fs: preserve ACL_DONT_CACHE state in forget_cached_acl()

Summary

In the Linux kernel, the following vulnerability has been resolved: fs: preserve ACL_DONT_CACHE state in forget_cached_acl() The ACL_DONT_CACHE state is meant to be a constant state for the inode for filesystems that want to opt out of posix acl caching. Commit facd61053cff1 ("fuse: fixes after adapting to new posix acl api") used this facility to opt out of posix acl caching for fuse inodes with fuse server that does not negotiate FUSE_POSIX_ACL (fc->posix_acl). The commit also takes care to gate the forget_all_cached_acls() call in fuse_set_acl() on fc->posix_acl because there is no need for it, but there are other placed in fuse code which call forget_all_cached_acls() unconditional to fc->posix_acl and those cause the loss of the ACL_DONT_CACHE state. This is not only a functional bug. Properly timed, a get_acl() from this fuse filesystem can return a stale cached value, as was observed in tests, because set_acl() does not invalidate the unintentional acl cache. We could fix this in fuse, but it actually makes no sense for the vfs helper forget_cached_acl() to invalidate the ACL_DONT_CACHE state, so let it not do that to fix fuse and future users of ACL_DONT_CACHE.

Severity

8.4 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Assigner

Linux mitre root

References

5 references

URL	Tags
https://git.kernel.org/stable/c/b98fad81f1202b0eb…
https://git.kernel.org/stable/c/834ddf899484a2f23…
https://git.kernel.org/stable/c/a019b074903b3ad0a…
https://git.kernel.org/stable/c/ca03a7984a34f4808…
https://git.kernel.org/stable/c/4b9a5458d02e214ef…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < b98fad81f1202b0eb26aacf3ff4cc7a21ed3b5bf (git) Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < 834ddf899484a2f23129080e8773bc04f4691d07 (git) Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < a019b074903b3ad0a9726087efd0e8291452023b (git) Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < ca03a7984a34f48085fd013e0d2cf4e6420b4acf (git) Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < 4b9a5458d02e214ef2b384124ca626e3e381d778 (git)
Linux	Linux	Affected: 6.2 Unaffected: 0 , < 6.2 (semver) Unaffected: 6.6.148 , ≤ 6.6.* (semver) Unaffected: 6.12.101 , ≤ 6.12.* (semver) Unaffected: 6.18.42 , ≤ 6.18.* (semver) Unaffected: 7.1.6 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/posix_acl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b98fad81f1202b0eb26aacf3ff4cc7a21ed3b5bf",
              "status": "affected",
              "version": "facd61053cff100973921d4d45d47cf53c747ec6",
              "versionType": "git"
            },
            {
              "lessThan": "834ddf899484a2f23129080e8773bc04f4691d07",
              "status": "affected",
              "version": "facd61053cff100973921d4d45d47cf53c747ec6",
              "versionType": "git"
            },
            {
              "lessThan": "a019b074903b3ad0a9726087efd0e8291452023b",
              "status": "affected",
              "version": "facd61053cff100973921d4d45d47cf53c747ec6",
              "versionType": "git"
            },
            {
              "lessThan": "ca03a7984a34f48085fd013e0d2cf4e6420b4acf",
              "status": "affected",
              "version": "facd61053cff100973921d4d45d47cf53c747ec6",
              "versionType": "git"
            },
            {
              "lessThan": "4b9a5458d02e214ef2b384124ca626e3e381d778",
              "status": "affected",
              "version": "facd61053cff100973921d4d45d47cf53c747ec6",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/posix_acl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.2"
            },
            {
              "lessThan": "6.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.148",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.101",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.148",
                  "versionStartIncluding": "6.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.101",
                  "versionStartIncluding": "6.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.42",
                  "versionStartIncluding": "6.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.6",
                  "versionStartIncluding": "6.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.2",
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                }
              ],
              "negate": false,
              "operator": "OR"
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs: preserve ACL_DONT_CACHE state in forget_cached_acl()\n\nThe ACL_DONT_CACHE state is meant to be a constant state for the inode\nfor filesystems that want to opt out of posix acl caching.\n\nCommit facd61053cff1 (\"fuse: fixes after adapting to new posix acl api\")\nused this facility to opt out of posix acl caching for fuse inodes with\nfuse server that does not negotiate FUSE_POSIX_ACL (fc-\u003eposix_acl).\n\nThe commit also takes care to gate the forget_all_cached_acls() call in\nfuse_set_acl() on fc-\u003eposix_acl because there is no need for it, but\nthere are other placed in fuse code which call forget_all_cached_acls()\nunconditional to fc-\u003eposix_acl and those cause the loss of the\nACL_DONT_CACHE state.\n\nThis is not only a functional bug. Properly timed, a get_acl() from this\nfuse filesystem can return a stale cached value, as was observed in tests,\nbecause set_acl() does not invalidate the unintentional acl cache.\n\nWe could fix this in fuse, but it actually makes no sense for the vfs\nhelper forget_cached_acl() to invalidate the ACL_DONT_CACHE state, so\nlet it not do that to fix fuse and future users of ACL_DONT_CACHE."
        }
      ],
      "metrics": [
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            "baseScore": 8.4,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires local VFS syscalls (getxattr, statx, open, read, write) on a FUSE-backed mount; the bug is in kernel ACL caching, not in a network protocol handler.\nAC:L - The attacker controls the full trigger sequence (stat/getattr to clear ACL_DONT_CACHE, getxattr to populate cache, ACL change, then access) and can drive timing with concurrent threads without depending on uncontrollable system state.\nPR:L - Any unprivileged local user who can mount or access a FUSE filesystem (fusermount, user namespaces, virtio-fs/SSHFS mounts with allow_other) can reach the vulnerable code paths on files within that mount.\nUI:N - Exploitation is fully attacker-driven through syscall sequences on the FUSE mount; no victim click, mount action, or other interactive cooperation is required beyond routine filesystem use.\nS:C - On virtio-fs/Kata/Firecracker shared host directories, stale kernel ACL enforcement can let a guest/container process access host-exported files beyond the permissions the host administrator intended, crossing that isolation boundary.\nC:H - Stale permissive cached ACLs cause check_acl()/posix_acl_permission() to authorize reads of files that should be denied after ACL tightening, enabling unauthorized disclosure of protected file contents on default_permissions mounts.\nI:H - The same stale ACL bypass lets an attacker obtain write permission enforced by the kernel VFS on files whose ACLs were subsequently restricted, enabling unauthorized modification of protected data.\nA:N - This is a stale-cache logic bug with no memory corruption, kernel crash, panic, or hang; observed impact is incorrect ACL enforcement and authorization bypass, not availability loss."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:59:43.618Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/ca03a7984a34f48085fd013e0d2cf4e6420b4acf"
        },
        {
          "url": "https://git.kernel.org/stable/c/4b9a5458d02e214ef2b384124ca626e3e381d778"
        }
      ],
      "title": "fs: preserve ACL_DONT_CACHE state in forget_cached_acl()",
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        "engine": "bippy-1.2.0"
      }
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68149",
    "datePublished": "2026-08-10T11:59:14.645Z",
    "dateReserved": "2026-07-30T09:28:09.371Z",
    "dateUpdated": "2026-08-17T04:59:43.618Z",
    "state": "PUBLISHED"
  },
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}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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GHSA-WJ9X-QHWH-XF9H

CVE-2026-68149 (GCVE-0-2026-68149)

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