{"api_version":"1","generated_at":"2026-09-13T16:13:49+00:00","cve":"CVE-2026-89662","urls":{"html":"https://cve.report/CVE-2026-89662","api":"https://cve.report/api/cve/CVE-2026-89662.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89662","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89662"},"summary":{"title":"NFSD: Prevent lock owner use-after-free during client teardown","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent lock owner use-after-free during client teardown\n\n__destroy_client() releases a client's open owners, but a lock owner\nwhose only reference is a blocked lock (nbl) stays on\ncl_ownerstr_hashtbl.  client_has_state() does not count a bare owner,\nso DESTROY_CLIENTID can reach __destroy_client() with such owners\npresent.\n\n__destroy_client() then walks the table, calling remove_blocked_locks()\non each owner without a reference.  Freeing a blocked lock drops the\nowner reference held via flc_owner.  The per-net laundromat reaps\nblocked locks from nn->blocked_locks_lru independently of client state.\nThe two paths share blocked_locks_lock only for the list splice, not\nthe owner's lifetime.  The laundromat therefore frees the owner as\n__destroy_client() dereferences it, a NULL dereference in\nremove_blocked_locks().\n\nnfsd4_release_lockowner() holds a reference across the same call;\n__destroy_client() does not.  Hold cl_lock across the walk, taking a\nreference and unhashing each owner, then drop it before\nremove_blocked_locks() and nfs4_put_stateowner(), which take\nblocked_locks_lock and cl_lock.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:52","updated_at":"2026-09-13 07:17:31"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431","name":"https://git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649","name":"https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743","name":"https://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd","name":"https://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89662","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89662","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 68ef3bc3166468678d5e1fdd216628c35bd1186f a6ead6fff3a7d03e49845f048f7000a2e0d34431 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 68ef3bc3166468678d5e1fdd216628c35bd1186f 4804c58f73a80d12df1de323bf97a164f6ee8743 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 68ef3bc3166468678d5e1fdd216628c35bd1186f 8cf4ff0a7c083dd5e0067f517d63979b74b66649 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 68ef3bc3166468678d5e1fdd216628c35bd1186f 5e2fa29d223a9a1e6a948e40b109d09081d1decd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e294c4c2d33b7307a89cdf31bec08a112d6a9297 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 797bfd05d4040fbf766198b3cfcc1838002cc890 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0f44e9da465ea259b6c9f31a627f3c50a16e1679 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.9.91 4.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.14.31 4.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.15.14 4.16 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.16","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.16 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* 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":{"cve_year":"2026","cve_id":"89662","cve":"CVE-2026-89662","epss":"0.002000000","percentile":"0.099730000","score_date":"2026-09-12","updated_at":"2026-09-13 00:08:17"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/nfsd/nfs4state.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a6ead6fff3a7d03e49845f048f7000a2e0d34431","status":"affected","version":"68ef3bc3166468678d5e1fdd216628c35bd1186f","versionType":"git"},{"lessThan":"4804c58f73a80d12df1de323bf97a164f6ee8743","status":"affected","version":"68ef3bc3166468678d5e1fdd216628c35bd1186f","versionType":"git"},{"lessThan":"8cf4ff0a7c083dd5e0067f517d63979b74b66649","status":"affected","version":"68ef3bc3166468678d5e1fdd216628c35bd1186f","versionType":"git"},{"lessThan":"5e2fa29d223a9a1e6a948e40b109d09081d1decd","status":"affected","version":"68ef3bc3166468678d5e1fdd216628c35bd1186f","versionType":"git"},{"status":"affected","version":"e294c4c2d33b7307a89cdf31bec08a112d6a9297","versionType":"git"},{"status":"affected","version":"797bfd05d4040fbf766198b3cfcc1838002cc890","versionType":"git"},{"status":"affected","version":"0f44e9da465ea259b6c9f31a627f3c50a16e1679","versionType":"git"},{"lessThan":"4.10","status":"affected","version":"4.9.91","versionType":"semver"},{"lessThan":"4.15","status":"affected","version":"4.14.31","versionType":"semver"},{"lessThan":"4.16","status":"affected","version":"4.15.14","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/nfsd/nfs4state.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.16"},{"lessThan":"4.16","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.109","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","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":"6.12.109","versionStartIncluding":"4.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"4.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"4.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"4.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.91","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.31","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15.14","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent lock owner use-after-free during client teardown\n\n__destroy_client() releases a client's open owners, but a lock owner\nwhose only reference is a blocked lock (nbl) stays on\ncl_ownerstr_hashtbl.  client_has_state() does not count a bare owner,\nso DESTROY_CLIENTID can reach __destroy_client() with such owners\npresent.\n\n__destroy_client() then walks the table, calling remove_blocked_locks()\non each owner without a reference.  Freeing a blocked lock drops the\nowner reference held via flc_owner.  The per-net laundromat reaps\nblocked locks from nn->blocked_locks_lru independently of client state.\nThe two paths share blocked_locks_lock only for the list splice, not\nthe owner's lifetime.  The laundromat therefore frees the owner as\n__destroy_client() dereferences it, a NULL dereference in\nremove_blocked_locks().\n\nnfsd4_release_lockowner() holds a reference across the same call;\n__destroy_client() does not.  Hold cl_lock across the walk, taking a\nreference and unhashing each owner, then drop it before\nremove_blocked_locks() and nfs4_put_stateowner(), which take\nblocked_locks_lock and cl_lock."}],"metrics":[{"cvssV3_1":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:N - The bug is in nfsd NFSv4.1 client teardown and blocked-lock handling, reached by remote COMPOUND RPCs on the in-kernel NFS server (TCP/UDP 2049). A network client drives EXCHANGE_ID, CREATE_SESSION, OPEN, blocking LOCK, DESTROY_SESSION, and DESTROY_CLIENTID into __destroy_client().\nAC:L - The attacker controls both sides of the race: one client holds a conflicting lock while another queues a blocked lock, then DESTROY_CLIENTID races with lock-grant/CB_NOTIFY_LOCK or the laundromat freeing that lockowner. Concurrent NFS requests create the race, and it can be retried.\nPR:N - Typical nfsd deployments use AUTH_SYS, which does not cryptographically authenticate the client. A remote peer that can reach an export can create NFSv4.1 state and issue DESTROY_CLIENTID without a local account or kernel capabilities on the server.\nUI:N - Exploitation requires only attacker-sent NFS RPCs against a running nfsd export. No victim user action such as mounting a filesystem or opening a local file on the server is required.\nS:U - The use-after-free occurs in kernel nfsd lock-owner state on the NFS server host and does not cross a separate security authority such as a VM, guest/host, or IOMMU boundary.\nC:H - This is a use-after-free of the nfs4_lockowner slab object. Reclaiming the freed owner lets an attacker control later reads of so_client and related pointers in remove_blocked_locks(), yielding a kernel information-disclosure primitive.\nI:H - The same UAF is exploitable for integrity: the freed lockowner includes so_ops function pointers and lo_blocked list heads, so heap reuse can hijack control flow or corrupt list pointers for an arbitrary kernel write.\nA:H - The bug is a kernel use-after-free of the lock owner and was observed as a NULL dereference in remove_blocked_locks(), which can oops or panic nfsd and take down the server."}]}],"providerMetadata":{"dateUpdated":"2026-09-13T06:32:44.342Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431"},{"url":"https://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743"},{"url":"https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649"},{"url":"https://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd"}],"title":"NFSD: Prevent lock owner use-after-free during client teardown","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89662","datePublished":"2026-09-11T19:45:49.833Z","dateReserved":"2026-09-11T19:38:34.744Z","dateUpdated":"2026-09-13T06:32:44.342Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:52","lastModifiedDate":"2026-09-13 07:17:31","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89662","Ordinal":"1","Title":"NFSD: Prevent lock owner use-after-free during client teardown","CVE":"CVE-2026-89662","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89662","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent lock owner use-after-free during client teardown\n\n__destroy_client() releases a client's open owners, but a lock owner\nwhose only reference is a blocked lock (nbl) stays on\ncl_ownerstr_hashtbl.  client_has_state() does not count a bare owner,\nso DESTROY_CLIENTID can reach __destroy_client() with such owners\npresent.\n\n__destroy_client() then walks the table, calling remove_blocked_locks()\non each owner without a reference.  Freeing a blocked lock drops the\nowner reference held via flc_owner.  The per-net laundromat reaps\nblocked locks from nn->blocked_locks_lru independently of client state.\nThe two paths share blocked_locks_lock only for the list splice, not\nthe owner's lifetime.  The laundromat therefore frees the owner as\n__destroy_client() dereferences it, a NULL dereference in\nremove_blocked_locks().\n\nnfsd4_release_lockowner() holds a reference across the same call;\n__destroy_client() does not.  Hold cl_lock across the walk, taking a\nreference and unhashing each owner, then drop it before\nremove_blocked_locks() and nfs4_put_stateowner(), which take\nblocked_locks_lock and cl_lock.","Type":"Description","Title":"NFSD: Prevent lock owner use-after-free during client teardown"}]}}}