{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89662", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.744Z", "datePublished": "2026-09-11T19:45:49.833Z", "dateUpdated": "2026-09-13T06:32:44.342Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-13T06:32:44.342Z"}, "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": {"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"}, "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."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/nfsd/nfs4state.c"], "versions": [{"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f", "lessThan": "a6ead6fff3a7d03e49845f048f7000a2e0d34431", "status": "affected", "versionType": "git"}, {"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f", "lessThan": "4804c58f73a80d12df1de323bf97a164f6ee8743", "status": "affected", "versionType": "git"}, {"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f", "lessThan": "8cf4ff0a7c083dd5e0067f517d63979b74b66649", "status": "affected", "versionType": "git"}, {"version": "68ef3bc3166468678d5e1fdd216628c35bd1186f", "lessThan": "5e2fa29d223a9a1e6a948e40b109d09081d1decd", "status": "affected", "versionType": "git"}, {"version": "e294c4c2d33b7307a89cdf31bec08a112d6a9297", "status": "affected", "versionType": "git"}, {"version": "797bfd05d4040fbf766198b3cfcc1838002cc890", "status": "affected", "versionType": "git"}, {"version": "0f44e9da465ea259b6c9f31a627f3c50a16e1679", "status": "affected", "versionType": "git"}, {"version": "4.9.91", "lessThan": "4.10", "status": "affected", "versionType": "semver"}, {"version": "4.14.31", "lessThan": "4.15", "status": "affected", "versionType": "semver"}, {"version": "4.15.14", "lessThan": "4.16", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/nfsd/nfs4state.c"], "versions": [{"version": "4.16", "status": "affected"}, {"version": "0", "lessThan": "4.16", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3-rc1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.12.109"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "7.3-rc1"}, {"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"}]}]}], "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"}}}}

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{"affected": [{"affectedData": [{"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"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "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."}], "id": "CVE-2026-89662", "lastModified": "2026-09-13T07:17:31.767", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-11T20:19:52.523", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel: NFSD use-after-free during client teardown leads to denial of service", "id": "2532486", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532486"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-476", "details": ["A flaw was found in the Linux kernel's Network File System Daemon (NFSD). During client teardown, a race condition can occur where a lock owner is freed while still being referenced, leading to a use-after-free vulnerability. This can result in a NULL dereference, potentially causing a system crash and a denial of service."], "name": "CVE-2026-89662", "public_date": "2026-09-11T19:45:49Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89662\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89662\nhttps://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743\nhttps://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd\nhttps://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649\nhttps://git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[68ef3bc3166468678d5e1fdd216628c35bd1186f,a6ead6fff3a7d03e49845f048f7000a2e0d34431)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[68ef3bc3166468678d5e1fdd216628c35bd1186f,4804c58f73a80d12df1de323bf97a164f6ee8743)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[68ef3bc3166468678d5e1fdd216628c35bd1186f,8cf4ff0a7c083dd5e0067f517d63979b74b66649)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[68ef3bc3166468678d5e1fdd216628c35bd1186f,5e2fa29d223a9a1e6a948e40b109d09081d1decd)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "e294c4c2d33b7307a89cdf31bec08a112d6a9297"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "797bfd05d4040fbf766198b3cfcc1838002cc890"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "0f44e9da465ea259b6c9f31a627f3c50a16e1679"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[4.9.91,4.10)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[4.14.31,4.15)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[4.15.14,4.16)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "4.16"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,4.16)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.12.109,6.12.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.18.50,6.18.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2.4,7.2.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-12T07:30:10.434744+00:00", "updated": "2026-09-13T12:00:04.824353+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}