{"id":"CVE-2026-31712","revision":null,"records":[{"revision":"8f7e984f996347279806ee9ca1fd8310","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-31712","aliases":[],"title":"ksmbd: require minimum ACE size in smb_check_perm_dacl()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: require minimum ACE size in smb_check_perm_dacl()\n\nBoth ACE-walk loops in smb_check_perm_dacl() only guard against an\nunder-sized remaining buffer, not against an ACE whose declared\n`ace->size` is smaller than the struct it claims to describe:\n\n if (offsetof(struct smb_ace, access_req) > aces_size)\n break;\n ace_size = le16_to_cpu(ace->size);\n if (ace_size > aces_size)\n break;\n\nThe first check only requires the 4-byte ACE header to be in bounds;\nit does not require access_req (4 bytes at offset 4) to be readable.\nAn attacker who has set a crafted DACL on a file they own can declare\nace->size == 4 with aces_size == 4, pass both checks, and then\n\n granted |= le32_to_cpu(ace->access_req); /* upper loop */\n compare_sids(&sid, &ace->sid); /* lower loop */\n\nreads access_req at offset 4 (OOB by up to 4 bytes) and ace->sid at\noffset 8 (OOB by up to CIFS_SID_BASE_SIZE + SID_MAX_SUB_AUTHORITIES\n* 4 bytes).\n\nTighten both loops to require\n\n ace_size >= offsetof(struct smb_ace, sid) + CIFS_SID_BASE_SIZE\n\nwhich is the smallest valid on-wire ACE layout (4-byte header +\n4-byte access_req + 8-byte sid base with zero sub-auths). Also\nreject ACEs whose sid.num_subauth exceeds SID_MAX_SUB_AUTHORITIES\nbefore letting compare_sids() dereference sub_auth[] entries.\n\nparse_sec_desc() already enforces an equivalent check (lines 441-448);\nsmb_check_perm_dacl() simply grew weaker validation over time.\n\nReachability: authenticated SMB client with permission to set an ACL\non a file. On a subsequent CREATE against that file, the kernel\nwalks the stored DACL via smb_check_perm_dacl() and triggers the\nOOB read. Not pre-auth, and the OOB read is not reflected to the\nattacker, but KASAN reports and kernel state corruption are\npossible.","state":0,"publishedAt":"2026-05-01T13:56:08.583+00:00","modifiedAt":"2026-10-15T01:18:08.369+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"fs/smb/server/smbacl.c\"\n ],\n \"versions\": [\n {\n \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n \"lessThan\": \"282cbbb476b9f35793452bc461934af4c7eca169\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n \"lessThan\": \"f20adc4ef7428bc485ee83fd1a592252fb87718b\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n \"lessThan\": \"325d4ac11f526cb8964cff14548ccf02d8c756d8\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n \"lessThan\": \"95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n \"lessThan\": \"90089584b2e25c4510b7b987387b4405f0673ece\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n \"lessThan\": \"151b1799861fde38087c08f613abc2843ef597b0\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n \"lessThan\": \"d07b26f39246a82399661936dd0c853983cfade7\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"fs/smb/server/smbacl.c\"\n ],\n \"versions\": [\n {\n \"version\": \"5.15\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"5.15\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.210\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.176\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.140\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.84\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.25\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.0.2\",\n \"lessThanOrEqual\": \"7.0.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H","score":8.3,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/282cbbb476b9f35793452bc461934af4c7eca169","https://git.kernel.org/stable/c/f20adc4ef7428bc485ee83fd1a592252fb87718b","https://git.kernel.org/stable/c/325d4ac11f526cb8964cff14548ccf02d8c756d8","https://git.kernel.org/stable/c/95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c","https://git.kernel.org/stable/c/90089584b2e25c4510b7b987387b4405f0673ece","https://git.kernel.org/stable/c/151b1799861fde38087c08f613abc2843ef597b0","https://git.kernel.org/stable/c/d07b26f39246a82399661936dd0c853983cfade7"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-31712","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-31712","identifiers":["CVE-2026-31712"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-09T18:04:49.9033842+00:00","complete":true,"records":1772,"lastAttemptAt":"2026-11-09T18:04:49.9033842+00:00","lastSuccessAt":"2026-11-09T18:04:51.4246251+00:00","error":null,"lastVerifiedAt":"2026-11-09T18:04:51.4246256+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-24e6fde7b744113daefb8f6135035fb8a5c69c9617c9c0d40574a0376532ffd3-da82b7f3c08c0a1c809bacbfac0a567c645c18f0205247304bfc7e4ee4c02653","complete":true,"records":421491,"lastAttemptAt":"2026-11-09T18:02:17.7227212+00:00","lastSuccessAt":"2026-11-09T18:02:17.6122603+00:00","error":null,"lastVerifiedAt":"2026-11-09T18:02:17.7227212+00:00","snapshotPublishedAt":"2026-11-09T17:19:01+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-83353c603c8b44ff880a9955a737c288","complete":false,"records":13655,"lastAttemptAt":"2026-11-09T18:17:25.0500848+00:00","lastSuccessAt":"2026-11-09T18:17:25.037+00:00","error":"6 identifier lookups failed; latest failures include HTTP 403. Other identifiers were checked independently.","lastVerifiedAt":"2026-11-09T18:17:25.037+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13294,"expectedIdentifiers":13707,"failedIdentifiers":6},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-09T18:04:49.9033842+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-09T18:04:49.9033842+00:00","lastSuccessAt":"2026-11-09T18:04:51.425345+00:00","error":null,"lastVerifiedAt":"2026-11-09T18:04:51.425345+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-b51e790980dd40318db1b79f996a5e64","complete":true,"records":13667,"lastAttemptAt":"2026-11-09T18:05:17.6533401+00:00","lastSuccessAt":"2026-11-09T18:05:17.648+00:00","error":null,"lastVerifiedAt":"2026-11-09T18:05:17.648+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13707,"expectedIdentifiers":13707,"failedIdentifiers":0},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-980593e6977a6d1b4fb1eed5a1ffe88a468736f89f0a06f710924ad59132c023","complete":true,"records":9914,"lastAttemptAt":"2026-11-09T18:04:49.7604938+00:00","lastSuccessAt":"2026-11-08T11:07:07.068788+00:00","error":null,"lastVerifiedAt":"2026-11-09T18:04:49.7604938+00:00","snapshotPublishedAt":"2026-11-08T11:02:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-712163772d637a9cfaa34d4241efb9e9d0ccd6149596c672c613d362f44af841","complete":true,"records":1971,"lastAttemptAt":"2026-11-09T18:02:23.1622896+00:00","lastSuccessAt":"2026-11-09T18:02:23.0088273+00:00","error":null,"lastVerifiedAt":"2026-11-09T18:02:23.1622896+00:00","snapshotPublishedAt":"2026-11-09T17:03:01+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-761ecc9061239b0da572dc9254c6f384c1d19339eb08408c436647a2f26129e9","complete":true,"records":3064,"lastAttemptAt":"2026-11-09T18:04:49.8693187+00:00","lastSuccessAt":"2026-11-09T17:05:03.4044794+00:00","error":null,"lastVerifiedAt":"2026-11-09T18:04:49.8693187+00:00","snapshotPublishedAt":"2026-11-09T16:33:20+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-e3fec63b2a5926ae79916bc9569f5c1069b095db78f2be319f909e69e8e6d7d3","complete":true,"records":231313,"lastAttemptAt":"2026-11-09T18:04:49.6325121+00:00","lastSuccessAt":"2026-11-09T18:04:48.1910635+00:00","error":null,"lastVerifiedAt":"2026-11-09T18:04:49.6325121+00:00","snapshotPublishedAt":"2026-11-09T17:33:10+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}