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

Vulnerability from cvelistv5 – Published: 2026-08-10 11:59 – Updated: 2026-08-17 04:59
VLAI
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
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < b98fad81f1202b0eb26aacf3ff4cc7a21ed3b5bf (git)
Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < 834ddf899484a2f23129080e8773bc04f4691d07 (git)
Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < a019b074903b3ad0a9726087efd0e8291452023b (git)
Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < ca03a7984a34f48085fd013e0d2cf4e6420b4acf (git)
Affected: facd61053cff100973921d4d45d47cf53c747ec6 , < 4b9a5458d02e214ef2b384124ca626e3e381d778 (git)
guessed Create a notification for this product.
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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          "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."
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            "version": "3.1"
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              "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."
            }
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    "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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            "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."
          }
        ],
        "id": "CVE-2026-68149",
        "lastModified": "2026-08-17T05:18:15.053",
        "metrics": {
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                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
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                "scope": "CHANGED",
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    "redhat_vex": {
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      "current_release_date": "2026-08-31T11:17:26+00:00",
      "cve": "CVE-2026-68149",
      "id": "CVE-2026-68149",
      "initial_release_date": "2026-08-10T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "93",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: fs: preserve ACL_DONT_CACHE state in forget_cached_acl()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-68149.json",
      "version": "3"
    },
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      "current_release_date": "2026-09-22T16:47:53Z",
      "cve": "CVE-2026-68149",
      "id": "CVE-2026-68149",
      "initial_release_date": "2026-08-17T16:29:49Z",
      "product_status:first_fixed": "60",
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      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-68149",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-68149.json",
      "version": "10"
    }
  }
}



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  • 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.
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  • 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.



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