{"id":"CVE-2026-53395","state":"PUBLISHED","title":"nfsd: fix dead ACL conflict guard in nfsd4_create","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix dead ACL conflict guard in nfsd4_create\n\nnfsd4_create() steals create->cr_dpacl/cr_pacl into the local\nnfsd_attrs via the designated initializer, then immediately sets the\nsource pointers to NULL. The subsequent conflict guard tests the\nalready-nilled source fields, making it permanently dead code:\n\n    if (create->cr_acl) {\n        if (create->cr_dpacl || create->cr_pacl)  /* always false */\n\nWhen a client encodes both FATTR4_WORD0_ACL and\nFATTR4_WORD2_POSIX_{DEFAULT,ACCESS}_ACL in the same CREATE fattr\nbitmap, nfsd4_acl_to_attr() overwrites attrs.na_pacl/na_dpacl without\nreleasing the originals, leaking two posix_acl slab objects per\nrequest. Repeated requests cause unbounded slab exhaustion.\n\nFix by checking attrs.na_dpacl/na_pacl (the stolen values) instead of\nthe nilled create->cr_dpacl/cr_pacl, matching the correct pattern\nalready used in nfsd4_setattr().","publishedAt":"2026-07-19T12:01:57.816Z","updatedAt":"2026-08-17T04:50:47.054Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d2ca50606f5f0235d7780c1cd73b6614a5d07620","status":"affected","lessThan":"8371cc5c0a2cc2a71b3dcfd47ff1f7fcfc526a5e","versionType":"git"},{"version":"d2ca50606f5f0235d7780c1cd73b6614a5d07620","status":"affected","lessThan":"a60f25a800846ab8e5a13f8a9d05111f2aee55a7","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4proc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.0","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4proc.c"]}],"references":["https://git.kernel.org/stable/c/8371cc5c0a2cc2a71b3dcfd47ff1f7fcfc526a5e","https://git.kernel.org/stable/c/a60f25a800846ab8e5a13f8a9d05111f2aee55a7"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53395.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53395","state":"PUBLISHED","datePublished":"2026-07-19T12:01:57.816Z","dateUpdated":"2026-08-17T04:50:47.054Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.402Z"},"containers":{"cna":{"title":"nfsd: fix dead ACL conflict guard in nfsd4_create","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix dead ACL conflict guard in nfsd4_create\n\nnfsd4_create() steals create->cr_dpacl/cr_pacl into the local\nnfsd_attrs via the designated initializer, then immediately sets the\nsource pointers to NULL. The subsequent conflict guard tests the\nalready-nilled source fields, making it permanently dead code:\n\n    if (create->cr_acl) {\n        if (create->cr_dpacl || create->cr_pacl)  /* always false */\n\nWhen a client encodes both FATTR4_WORD0_ACL and\nFATTR4_WORD2_POSIX_{DEFAULT,ACCESS}_ACL in the same CREATE fattr\nbitmap, nfsd4_acl_to_attr() overwrites attrs.na_pacl/na_dpacl without\nreleasing the originals, leaking two posix_acl slab objects per\nrequest. Repeated requests cause unbounded slab exhaustion.\n\nFix by checking attrs.na_dpacl/na_pacl (the stolen values) instead of\nthe nilled create->cr_dpacl/cr_pacl, matching the correct pattern\nalready used in nfsd4_setattr()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d2ca50606f5f0235d7780c1cd73b6614a5d07620","status":"affected","lessThan":"8371cc5c0a2cc2a71b3dcfd47ff1f7fcfc526a5e","versionType":"git"},{"version":"d2ca50606f5f0235d7780c1cd73b6614a5d07620","status":"affected","lessThan":"a60f25a800846ab8e5a13f8a9d05111f2aee55a7","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4proc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.0","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4proc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/8371cc5c0a2cc2a71b3dcfd47ff1f7fcfc526a5e"},{"url":"https://git.kernel.org/stable/c/a60f25a800846ab8e5a13f8a9d05111f2aee55a7"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerability is reached through the in-kernel NFS server (nfsd) processing remotely submitted NFSv4 COMPOUND requests containing OP_CREATE over the network (TCP/2049).\nAC:L - An attacker can reliably trigger the leak by sending CREATE operations with both FATTR4_WORD0_ACL and FATTR4_WORD2_POSIX_DEFAULT/ACCESS_ACL set in the fattr bitmap; no race or uncontrollable conditions are required.\nPR:N - Exploitation requires only network reachability to nfsd and standard NFSv4 client authentication to an export; no elevated Linux privileges on the server are needed beyond being an authorized NFS client.\nUI:N - The leak is triggered entirely by crafted NFS protocol requests with no action required from a human user on the server.\nS:U - Impact is confined to kernel memory exhaustion on the NFS server; it does not cross a security boundary such as a VM or sandbox escape.\nC:N - The bug causes reference leaks of posix_acl slab objects only; there is no out-of-bounds access, use-after-free, or other memory corruption that could disclose data.\nI:N - No data modification or memory corruption occurs; the only effect is unreleased kernel heap allocations.\nA:H - Each malicious CREATE leaks two posix_acl slab objects, and repeated requests cause unbounded slab exhaustion that can render the NFS server and potentially the entire host unavailable through OOM conditions."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:50:47.054Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0","versionEndExcluding":"7.1.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}