{ "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": "2026-10-19T08:50:33.792Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:50:33.792Z" }, "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": "42d7954b0a1907d4ef122aef94561952a033cdc3", "status": "affected", "versionType": "git" }, { "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f", "lessThan": "bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a", "status": "affected", "versionType": "git" }, { "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f", "lessThan": "b8bad5a11416b26cc7fd4b18fba46d75ff636558", "status": "affected", "versionType": "git" }, { "version": "68ef3bc3166468678d5e1fdd216628c35bd1186f", "lessThan": "1ce74d1b7770e69735e8f8e509807af4ff9c8ee7", "status": "affected", "versionType": "git" }, { "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": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "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", "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": "5.10.270" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "5.15.221" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.6.157" }, { "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" }, { "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/42d7954b0a1907d4ef122aef94561952a033cdc3" }, { "url": "https://git.kernel.org/stable/c/bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a" }, { "url": "https://git.kernel.org/stable/c/b8bad5a11416b26cc7fd4b18fba46d75ff636558" }, { "url": "https://git.kernel.org/stable/c/1ce74d1b7770e69735e8f8e509807af4ff9c8ee7" }, { "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" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-89662", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:25:37.406747Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:47.751Z" } } ] } }