{"api_version":"1","generated_at":"2026-09-11T22:05:30+00:00","cve":"CVE-2026-89695","urls":{"html":"https://cve.report/CVE-2026-89695","api":"https://cve.report/api/cve/CVE-2026-89695.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89695","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89695"},"summary":{"title":"nfsd: cap decoded POSIX ACL count to bound sort cost","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: cap decoded POSIX ACL count to bound sort cost\n\nnfsd4_decode_posixacl() reads a u32 entry count off the wire and passes\nit straight to posix_acl_alloc() and sort_pacl_range(). The latter is\nan O(n^2) bubble sort, so a client-chosen count drives unbounded CPU in\nthe server's compound processing path.\n\n    nfsd4_decode_posixacl()\n      xdr_stream_decode_u32(&count)       /* uncapped u32 */\n      posix_acl_alloc(count, GFP_KERNEL)\n      sort_pacl_range(*acl, 0, count - 1) /* O(n^2) bubble sort */\n\nThe encoder side in the same file already rejects ACLs whose a_count\nexceeds NFS_ACL_MAX_ENTRIES, but the decoder introduced in commit\n5fc51dfc2eb1 (\"NFSD: Add support for XDR decoding POSIX draft ACLs\")\nomitted the symmetric check.\n\nFix by rejecting a wire count greater than NFS_ACL_MAX_ENTRIES with\nnfserr_inval, before any allocation, so the sort is bounded by\nNFS_ACL_MAX_ENTRIES^2 comparisons.\n\nWhile we're in here, also fix the nfserr_resource return if\nposix_acl_alloc() fails. That's not a legal error code for v4.1+. Change\nit to return nfserr_jukebox as that's more appropriate for memory\nallocation failures.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:56","updated_at":"2026-09-11 20:19:56"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/ea14d71d6ecb925673761bcf79f781f7dc9042cc","name":"https://git.kernel.org/stable/c/ea14d71d6ecb925673761bcf79f781f7dc9042cc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4bc1108e876153a2dd6d874052b99182c3603135","name":"https://git.kernel.org/stable/c/4bc1108e876153a2dd6d874052b99182c3603135","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89695","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89695","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05 ea14d71d6ecb925673761bcf79f781f7dc9042cc git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05 4bc1108e876153a2dd6d874052b99182c3603135 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.0","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/nfsd/nfs4xdr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"ea14d71d6ecb925673761bcf79f781f7dc9042cc","status":"affected","version":"5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05","versionType":"git"},{"lessThan":"4bc1108e876153a2dd6d874052b99182c3603135","status":"affected","version":"5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/nfsd/nfs4xdr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.0"},{"lessThan":"7.0","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"7.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"7.0","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: cap decoded POSIX ACL count to bound sort cost\n\nnfsd4_decode_posixacl() reads a u32 entry count off the wire and passes\nit straight to posix_acl_alloc() and sort_pacl_range(). The latter is\nan O(n^2) bubble sort, so a client-chosen count drives unbounded CPU in\nthe server's compound processing path.\n\n    nfsd4_decode_posixacl()\n      xdr_stream_decode_u32(&count)       /* uncapped u32 */\n      posix_acl_alloc(count, GFP_KERNEL)\n      sort_pacl_range(*acl, 0, count - 1) /* O(n^2) bubble sort */\n\nThe encoder side in the same file already rejects ACLs whose a_count\nexceeds NFS_ACL_MAX_ENTRIES, but the decoder introduced in commit\n5fc51dfc2eb1 (\"NFSD: Add support for XDR decoding POSIX draft ACLs\")\nomitted the symmetric check.\n\nFix by rejecting a wire count greater than NFS_ACL_MAX_ENTRIES with\nnfserr_inval, before any allocation, so the sort is bounded by\nNFS_ACL_MAX_ENTRIES^2 comparisons.\n\nWhile we're in here, also fix the nfserr_resource return if\nposix_acl_alloc() fails. That's not a legal error code for v4.1+. Change\nit to return nfserr_jukebox as that's more appropriate for memory\nallocation failures."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:46:14.258Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/ea14d71d6ecb925673761bcf79f781f7dc9042cc"},{"url":"https://git.kernel.org/stable/c/4bc1108e876153a2dd6d874052b99182c3603135"}],"title":"nfsd: cap decoded POSIX ACL count to bound sort cost","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89695","datePublished":"2026-09-11T19:46:14.258Z","dateReserved":"2026-09-11T19:38:34.750Z","dateUpdated":"2026-09-11T19:46:14.258Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:56","lastModifiedDate":"2026-09-11 20:19:56","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89695","Ordinal":"1","Title":"nfsd: cap decoded POSIX ACL count to bound sort cost","CVE":"CVE-2026-89695","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89695","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: cap decoded POSIX ACL count to bound sort cost\n\nnfsd4_decode_posixacl() reads a u32 entry count off the wire and passes\nit straight to posix_acl_alloc() and sort_pacl_range(). The latter is\nan O(n^2) bubble sort, so a client-chosen count drives unbounded CPU in\nthe server's compound processing path.\n\n    nfsd4_decode_posixacl()\n      xdr_stream_decode_u32(&count)       /* uncapped u32 */\n      posix_acl_alloc(count, GFP_KERNEL)\n      sort_pacl_range(*acl, 0, count - 1) /* O(n^2) bubble sort */\n\nThe encoder side in the same file already rejects ACLs whose a_count\nexceeds NFS_ACL_MAX_ENTRIES, but the decoder introduced in commit\n5fc51dfc2eb1 (\"NFSD: Add support for XDR decoding POSIX draft ACLs\")\nomitted the symmetric check.\n\nFix by rejecting a wire count greater than NFS_ACL_MAX_ENTRIES with\nnfserr_inval, before any allocation, so the sort is bounded by\nNFS_ACL_MAX_ENTRIES^2 comparisons.\n\nWhile we're in here, also fix the nfserr_resource return if\nposix_acl_alloc() fails. That's not a legal error code for v4.1+. Change\nit to return nfserr_jukebox as that's more appropriate for memory\nallocation failures.","Type":"Description","Title":"nfsd: cap decoded POSIX ACL count to bound sort cost"}]}}}