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CVE-2026-89671 (GCVE-0-2026-89671)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-14 12:01
VLAI
Title
nfsd: gate nfs3 setacl by argp->mask
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: gate nfs3 setacl by argp->mask nfsd3_proc_setacl() calls set_posix_acl() unconditionally for both ACL_TYPE_ACCESS and ACL_TYPE_DEFAULT, passing argp->acl_access and argp->acl_default verbatim. The NFSv3 ACL decoder only populates those pointers when the corresponding mask bit is set: nfs3svc_decode_setaclargs() if (args->mask & NFS_ACL) decode into acl_access if (args->mask & NFS_DFACL) decode into acl_default /* otherwise the pointer stays NULL (pc_argzero) */ nfsd3_proc_setacl() set_posix_acl(.., ACL_TYPE_ACCESS, argp->acl_access) set_posix_acl(.., ACL_TYPE_DEFAULT, argp->acl_default) set_posix_acl(idmap, dentry, type, NULL) is the VFS "remove this ACL type" operation. A NULL pointer that means "the client did not send this arm" is therefore indistinguishable from "the client asked to remove this ACL". A SETACL with mask=NFS_ACL silently drops the directory's default ACL; mask=0 drops both. The sibling nfsd3_proc_getacl() already consults argp->mask before touching each arm; mirror that in setacl. Fix by wrapping each set_posix_acl() call in the matching mask bit check and initializing error to 0 before inode_lock so that a request with neither bit set leaves the on-disk ACLs untouched and returns nfs_ok. The out_drop_lock path and the unconditional posix_acl_release() at out: are preserved; both NULL-tolerate the skipped arms.
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < 3be1d8611dae4829e4608007db29f4a8748c37b2 (git)
Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < 68a80b26efdff1d09f8ae1773c6a915abb9e191d (git)
Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < b3bff820d068ea59767d4e91a3258231a879da5f (git)
Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < ff99ed007f065198fd723152405c22aa558f700b (git)
Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < 453d7198a0ab07a12d46e0575861ac7b932da17e (git)
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Linux Linux Affected: 2.6.13
Unaffected: 0 , < 2.6.13 (semver)
Unaffected: 6.6.157 , ≤ 6.6.* (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
  "containers": {
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      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
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              "version": "7.2.4",
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              "status": "unaffected",
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      "cpeApplicability": [
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                  "versionEndExcluding": "6.6.157",
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: gate nfs3 setacl by argp-\u003emask\n\nnfsd3_proc_setacl() calls set_posix_acl() unconditionally for both\nACL_TYPE_ACCESS and ACL_TYPE_DEFAULT, passing argp-\u003eacl_access and\nargp-\u003eacl_default verbatim. The NFSv3 ACL decoder only populates\nthose pointers when the corresponding mask bit is set:\n\n    nfs3svc_decode_setaclargs()\n      if (args-\u003emask \u0026 NFS_ACL)    decode into acl_access\n      if (args-\u003emask \u0026 NFS_DFACL)  decode into acl_default\n      /* otherwise the pointer stays NULL (pc_argzero) */\n\n    nfsd3_proc_setacl()\n      set_posix_acl(.., ACL_TYPE_ACCESS,  argp-\u003eacl_access)\n      set_posix_acl(.., ACL_TYPE_DEFAULT, argp-\u003eacl_default)\n\nset_posix_acl(idmap, dentry, type, NULL) is the VFS \"remove this\nACL type\" operation. A NULL pointer that means \"the client did not\nsend this arm\" is therefore indistinguishable from \"the client\nasked to remove this ACL\". A SETACL with mask=NFS_ACL silently\ndrops the directory\u0027s default ACL; mask=0 drops both.\n\nThe sibling nfsd3_proc_getacl() already consults argp-\u003emask before\ntouching each arm; mirror that in setacl.\n\nFix by wrapping each set_posix_acl() call in the matching mask bit\ncheck and initializing error to 0 before inode_lock so that a\nrequest with neither bit set leaves the on-disk ACLs untouched and\nreturns nfs_ok. The out_drop_lock path and the unconditional\nposix_acl_release() at out: are preserved; both NULL-tolerate the\nskipped arms."
        }
      ],
      "metrics": [
        {
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          },
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            {
              "lang": "en",
              "value": "AV:N - nfsd3_proc_setacl() is NFSACL v3 SETACL (RPC program 100227) on the in-kernel NFS server, reached over TCP/UDP (typically port 2049) from a remote peer; no local syscall or physical access is required.\nAC:L - A single SETACL with mask omitting NFS_ACL and/or NFS_DFACL reliably deletes the corresponding POSIX ACL; there is no race or attacker-uncontrollable layout, and CONFIG_NFSD_V3_ACL is enabled on common distro NFS server kernels.\nPR:N - Default nfsd exports accept AUTH_UNIX and AUTH_NULL with no shared secret; AUTH_UNIX UIDs are attacker-chosen, so the caller spoofs the inode owner to pass inode_owner_or_capable() without any account on the server.\nUI:N - The attacker triggers the flaw by sending crafted NFSACL SETACL RPCs; no victim must mount a filesystem, open a file, or otherwise interact.\nS:U - Impact stays on POSIX ACL metadata of the exported filesystem in the same kernel/host security authority; this is not a VM escape, IOMMU bypass, or sandbox breakout.\nC:H - Removing an access ACL drops named-user/group entries that may be the only restriction beyond mode bits, and removing a directory default ACL stops inheritance of restrictive policy, so ACL-protected file contents can become readable.\nI:H - set_posix_acl(..., NULL) is the VFS remove-ACL operation, so an omitted mask bit silently deletes that ACL type on disk; mask=NFS_ACL strips the default ACL and mask=0 strips both, destroying access-control metadata.\nA:N - The path performs a defined VFS ACL-remove and does not oops, panic, hang, deadlock, or leak kernel memory, so nfsd and the host remain available."
            }
          ]
        }
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        "dateUpdated": "2026-09-14T12:01:56.734Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/453d7198a0ab07a12d46e0575861ac7b932da17e"
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      "title": "nfsd: gate nfs3 setacl by argp-\u003emask",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89671",
    "datePublished": "2026-09-11T19:45:56.604Z",
    "dateReserved": "2026-09-11T19:38:34.746Z",
    "dateUpdated": "2026-09-14T12:01:56.734Z",
    "state": "PUBLISHED"
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      "cve": "CVE-2026-89671",
      "date": "2026-09-15",
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      "percentile": "0.40568"
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      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "nfsd: gate nfs3 setacl by argp-\u003emask",
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      "version": "2"
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The NFSv3 ACL decoder only populates\\nthose pointers when the corresponding mask bit is set:\\n\\n    nfs3svc_decode_setaclargs()\\n      if (args-\u003emask \u0026 NFS_ACL)    decode into acl_access\\n      if (args-\u003emask \u0026 NFS_DFACL)  decode into acl_default\\n      /* otherwise the pointer stays NULL (pc_argzero) */\\n\\n    nfsd3_proc_setacl()\\n      set_posix_acl(.., ACL_TYPE_ACCESS,  argp-\u003eacl_access)\\n      set_posix_acl(.., ACL_TYPE_DEFAULT, argp-\u003eacl_default)\\n\\nset_posix_acl(idmap, dentry, type, NULL) is the VFS \\\"remove this\\nACL type\\\" operation. A NULL pointer that means \\\"the client did not\\nsend this arm\\\" is therefore indistinguishable from \\\"the client\\nasked to remove this ACL\\\". A SETACL with mask=NFS_ACL silently\\ndrops the directory\u0027s default ACL; mask=0 drops both.\\n\\nThe sibling nfsd3_proc_getacl() already consults argp-\u003emask before\\ntouching each arm; mirror that in setacl.\\n\\nFix by wrapping each set_posix_acl() call in the matching mask bit\\ncheck and initializing error to 0 before inode_lock so that a\\nrequest with neither bit set leaves the on-disk ACLs untouched and\\nreturns nfs_ok. The out_drop_lock path and the unconditional\\nposix_acl_release() at out: are preserved; both NULL-tolerate the\\nskipped arms.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/nfsd/nfs3acl.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"a257cdd0e2179630d3201c32ba14d7fcb3c3a055\",\"lessThan\":\"3be1d8611dae4829e4608007db29f4a8748c37b2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a257cdd0e2179630d3201c32ba14d7fcb3c3a055\",\"lessThan\":\"68a80b26efdff1d09f8ae1773c6a915abb9e191d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a257cdd0e2179630d3201c32ba14d7fcb3c3a055\",\"lessThan\":\"b3bff820d068ea59767d4e91a3258231a879da5f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a257cdd0e2179630d3201c32ba14d7fcb3c3a055\",\"lessThan\":\"ff99ed007f065198fd723152405c22aa558f700b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a257cdd0e2179630d3201c32ba14d7fcb3c3a055\",\"lessThan\":\"453d7198a0ab07a12d46e0575861ac7b932da17e\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/nfsd/nfs3acl.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2.6.13\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"2.6.13\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.157\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.109\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.50\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N\",\"baseScore\":9.1,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":3.9,\"impactScore\":5.2}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/3be1d8611dae4829e4608007db29f4a8748c37b2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/453d7198a0ab07a12d46e0575861ac7b932da17e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/68a80b26efdff1d09f8ae1773c6a915abb9e191d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b3bff820d068ea59767d4e91a3258231a879da5f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ff99ed007f065198fd723152405c22aa558f700b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-13T07:00:24+00:00",
      "cve": "CVE-2026-89671",
      "id": "CVE-2026-89671",
      "initial_release_date": "2026-09-11T19:45:56.604000+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel: NFSv3 `nfsd` allows unauthorized ACL removal via crafted SETACL requests.",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89671.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-16T00:00:38Z",
      "cve": "CVE-2026-89671",
      "id": "CVE-2026-89671",
      "initial_release_date": "2026-09-12T16:23:56Z",
      "product_status:known_affected": "353",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89671",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89671.json",
      "version": "6"
    }
  }
}



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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.

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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 exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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