{"id":"CVE-2026-72170","revision":null,"records":[{"revision":"c7ad2cca3def4e08a8766d24a23db521","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-72170","aliases":[],"title":"9p: skip nlink update in cacheless mode to fix WARN_ON","description":"In the Linux kernel, the following vulnerability has been resolved:\n\n9p: skip nlink update in cacheless mode to fix WARN_ON\n\nv9fs_dec_count() unconditionally calls drop_nlink() on regular files,\neven when the inode's nlink is already zero. In cacheless mode the\nclient refetches inode metadata from the server (the source of truth)\non every operation, so by the time v9fs_remove() returns, the locally\ncached nlink may already reflect the post-unlink value:\n\n 1. Client initiates unlink, server processes it and sets nlink to 0\n 2. Client refetches inode metadata (nlink=0) before unlink returns\n 3. Client's v9fs_remove() completes successfully\n 4. Client calls v9fs_dec_count() which calls drop_nlink() on nlink=0\n\nThis race is easily triggered under heavy unlink workloads, such as\nstress-ng's unlink stressor, producing the following warning:\n\n WARNING: fs/inode.c:417 at drop_nlink+0x4c/0xc8\n Call trace:\n drop_nlink+0x4c/0xc8\n v9fs_remove+0x1e0/0x250 [9p]\n v9fs_vfs_unlink+0x20/0x38 [9p]\n vfs_unlink+0x13c/0x258\n ...\n\nIn cacheless mode the server is authoritative and the inode is on its\nway out, so locally adjusting nlink buys nothing. Skip v9fs_dec_count()\nentirely when neither CACHE_META nor CACHE_LOOSE is set, which both\navoids the warning and removes a class of nlink races (two concurrent\nunlinkers observing nlink > 0 and both calling drop_nlink()) that an\nnlink == 0 guard alone would only narrow rather than close.","state":0,"publishedAt":"2026-08-15T05:53:36.332+00:00","modifiedAt":"2026-10-16T18:45:00.097+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/9p/vfs_inode.c\"\n ],\n \"versions\": [\n {\n \"version\": \"ac89b2ef9b55924bcf922251f043ba73a32d05bb\",\n \"lessThan\": \"6086469f7d469549bfd070348b717a6e43736200\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac89b2ef9b55924bcf922251f043ba73a32d05bb\",\n \"lessThan\": \"ab257019cb72f467b55c95384d99c94e3908b928\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac89b2ef9b55924bcf922251f043ba73a32d05bb\",\n \"lessThan\": \"4ec4ebe40c82cb4c60756732f6593055d010c59c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac89b2ef9b55924bcf922251f043ba73a32d05bb\",\n \"lessThan\": \"a5a682b016ef5b5384e28f6d652d47a8f8e73d37\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac89b2ef9b55924bcf922251f043ba73a32d05bb\",\n \"lessThan\": \"de79c3f3643841b8659a71958df7cf2a66bfd409\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac89b2ef9b55924bcf922251f043ba73a32d05bb\",\n \"lessThan\": \"8d610017c992de705b304d3d727a6e3a86af6149\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac89b2ef9b55924bcf922251f043ba73a32d05bb\",\n \"lessThan\": \"8faccac11e1369adddf5d80f4a45af93f13b2e1a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac89b2ef9b55924bcf922251f043ba73a32d05bb\",\n \"lessThan\": \"574aa0b4799470ac814479f1138d19efe6262255\",\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/9p/vfs_inode.c\"\n ],\n \"versions\": [\n {\n \"version\": \"4.17\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"4.17\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.266\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.217\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.184\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.145\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.97\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.40\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1.5\",\n \"lessThanOrEqual\": \"7.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/6086469f7d469549bfd070348b717a6e43736200","https://git.kernel.org/stable/c/ab257019cb72f467b55c95384d99c94e3908b928","https://git.kernel.org/stable/c/4ec4ebe40c82cb4c60756732f6593055d010c59c","https://git.kernel.org/stable/c/a5a682b016ef5b5384e28f6d652d47a8f8e73d37","https://git.kernel.org/stable/c/de79c3f3643841b8659a71958df7cf2a66bfd409","https://git.kernel.org/stable/c/8d610017c992de705b304d3d727a6e3a86af6149","https://git.kernel.org/stable/c/8faccac11e1369adddf5d80f4a45af93f13b2e1a","https://git.kernel.org/stable/c/574aa0b4799470ac814479f1138d19efe6262255"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72170","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-72170","identifiers":["CVE-2026-72170"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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Not a global EPSS backfill.","generation":"2026-11-09T09:04:02.9162191+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-09T09:04:02.9162191+00:00","lastSuccessAt":"2026-11-09T09:04:03.197028+00:00","error":null,"lastVerifiedAt":"2026-11-09T09:04:03.1970284+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-156d67f0b09643159ff4bd684ee896db","complete":true,"records":13666,"lastAttemptAt":"2026-11-09T09:04:03.6692263+00:00","lastSuccessAt":"2026-11-09T07:04:26.209+00:00","error":null,"lastVerifiedAt":"2026-11-09T07:04:26.209+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13706,"expectedIdentifiers":13706,"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":"2026-11-09T09:04:02.7750454+00:00","lastSuccessAt":"2026-11-08T11:07:07.068788+00:00","error":null,"lastVerifiedAt":"2026-11-09T09:04:02.7750454+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-fde804134ecdda0ddd5ff5c26ee1fff5a6fa659311f7ef2e51c6ad54964db0e2","complete":true,"records":1971,"lastAttemptAt":"2026-11-09T09:02:14.7586225+00:00","lastSuccessAt":"2026-11-06T19:03:17.0399903+00:00","error":null,"lastVerifiedAt":"2026-11-09T09:02:14.7586225+00:00","snapshotPublishedAt":"2026-11-06T18:17:57+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-f6d341f4320a5a0c059c28102ee651c3dd06abc87b84d2bafa4e2a823ec07d35","complete":true,"records":3056,"lastAttemptAt":"2026-11-09T09:04:02.8843128+00:00","lastSuccessAt":"2026-11-09T05:02:23.1539412+00:00","error":null,"lastVerifiedAt":"2026-11-09T09:04:02.8843128+00:00","snapshotPublishedAt":"2026-11-09T04:47:48+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-d0592215f99679f1cc533698c7c7cf50c306057d38021110cecb15015dc78137","complete":true,"records":231297,"lastAttemptAt":"2026-11-09T09:04:02.4970329+00:00","lastSuccessAt":"2026-11-09T09:04:00.7848047+00:00","error":null,"lastVerifiedAt":"2026-11-09T09:04:02.4970329+00:00","snapshotPublishedAt":"2026-11-09T08:33:22+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}