{"id":"CVE-2026-89671","state":"PUBLISHED","title":"nfsd: gate nfs3 setacl by argp->mask","description":"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.","publishedAt":"2026-09-11T19:45:56.604Z","updatedAt":"2026-10-30T12:32:36.627Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"beeb33152873ad40692bd255b562966f8ba43dbd","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"3be1d8611dae4829e4608007db29f4a8748c37b2","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"68a80b26efdff1d09f8ae1773c6a915abb9e191d","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"b3bff820d068ea59767d4e91a3258231a879da5f","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"ff99ed007f065198fd723152405c22aa558f700b","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"453d7198a0ab07a12d46e0575861ac7b932da17e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs3acl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.13","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs3acl.c"]}],"references":["https://git.kernel.org/stable/c/beeb33152873ad40692bd255b562966f8ba43dbd","https://git.kernel.org/stable/c/3be1d8611dae4829e4608007db29f4a8748c37b2","https://git.kernel.org/stable/c/68a80b26efdff1d09f8ae1773c6a915abb9e191d","https://git.kernel.org/stable/c/b3bff820d068ea59767d4e91a3258231a879da5f","https://git.kernel.org/stable/c/ff99ed007f065198fd723152405c22aa558f700b","https://git.kernel.org/stable/c/453d7198a0ab07a12d46e0575861ac7b932da17e"],"weaknesses":[],"ingestedAt":"2026-10-30T12:52:04.348Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89671.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89671","state":"PUBLISHED","datePublished":"2026-09-11T19:45:56.604Z","dateUpdated":"2026-10-30T12:32:36.627Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.746Z"},"containers":{"cna":{"title":"nfsd: gate nfs3 setacl by argp->mask","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"beeb33152873ad40692bd255b562966f8ba43dbd","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"3be1d8611dae4829e4608007db29f4a8748c37b2","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"68a80b26efdff1d09f8ae1773c6a915abb9e191d","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"b3bff820d068ea59767d4e91a3258231a879da5f","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"ff99ed007f065198fd723152405c22aa558f700b","versionType":"git"},{"version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","status":"affected","lessThan":"453d7198a0ab07a12d46e0575861ac7b932da17e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs3acl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.13","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs3acl.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/beeb33152873ad40692bd255b562966f8ba43dbd"},{"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:32:36.627Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.13","versionEndExcluding":"6.1.191"},{"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","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"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:26:48.048Z"}}]}}}