{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89671", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.746Z", "datePublished": "2026-09-11T19:45:56.604Z", "dateUpdated": "2026-10-19T08:50:44.635Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:50:44.635Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: gate nfs3 setacl by argp->mask\n\nnfsd3_proc_setacl() calls set_posix_acl() unconditionally for both\nACL_TYPE_ACCESS and ACL_TYPE_DEFAULT, passing argp->acl_access and\nargp->acl_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->mask & NFS_ACL) decode into acl_access\n if (args->mask & 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->acl_access)\n set_posix_acl(.., ACL_TYPE_DEFAULT, argp->acl_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's default ACL; mask=0 drops both.\n\nThe sibling nfsd3_proc_getacl() already consults argp->mask 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": [ { "cvssV3_1": { "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" }, "scenarios": [ { "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/nfsd/nfs3acl.c" ], "versions": [ { "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055", "lessThan": "3be1d8611dae4829e4608007db29f4a8748c37b2", "status": "affected", "versionType": "git" }, { "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055", "lessThan": "68a80b26efdff1d09f8ae1773c6a915abb9e191d", "status": "affected", "versionType": "git" }, { "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055", "lessThan": "b3bff820d068ea59767d4e91a3258231a879da5f", "status": "affected", "versionType": "git" }, { "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055", "lessThan": "ff99ed007f065198fd723152405c22aa558f700b", "status": "affected", "versionType": "git" }, { "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055", "lessThan": "453d7198a0ab07a12d46e0575861ac7b932da17e", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/nfsd/nfs3acl.c" ], "versions": [ { "version": "2.6.13", "status": "affected" }, { "version": "0", "lessThan": "2.6.13", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.13", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.13", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.13", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.13", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.13", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3be1d8611dae4829e4608007db29f4a8748c37b2" }, { "url": "https://git.kernel.org/stable/c/68a80b26efdff1d09f8ae1773c6a915abb9e191d" }, { "url": "https://git.kernel.org/stable/c/b3bff820d068ea59767d4e91a3258231a879da5f" }, { "url": "https://git.kernel.org/stable/c/ff99ed007f065198fd723152405c22aa558f700b" }, { "url": "https://git.kernel.org/stable/c/453d7198a0ab07a12d46e0575861ac7b932da17e" } ], "title": "nfsd: gate nfs3 setacl by argp->mask", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-89671", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:25:43.543380Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:48.048Z" } } ] } }