{"id":"CVE-2026-89662","title":"NFSD: Prevent lock owner use-after-free during client teardown","summary":"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 l…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-476"],"vendor":"Linux","product":"Linux","affected":["Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 42d7954b0a1907d4ef122aef94561952a033cdc3","Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a","Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < b8bad5a11416b26cc7fd4b18fba46d75ff636558","Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 1ce74d1b7770e69735e8f8e509807af4ff9c8ee7","Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < a6ead6fff3a7d03e49845f048f7000a2e0d34431","Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 4804c58f73a80d12df1de323bf97a164f6ee8743","Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 8cf4ff0a7c083dd5e0067f517d63979b74b66649","Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 5e2fa29d223a9a1e6a948e40b109d09081d1decd","Linux e294c4c2d33b7307a89cdf31bec08a112d6a9297","Linux 797bfd05d4040fbf766198b3cfcc1838002cc890","Linux 0f44e9da465ea259b6c9f31a627f3c50a16e1679","Linux >= 4.9.91 < 4.10","Linux >= 4.14.31 < 4.15","Linux >= 4.15.14 < 4.16","Linux 4.16"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-16T19:25:37.406747Z"},"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:50:33.792Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89662","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"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89662.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89662"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532486"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89662"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89662"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89662.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00694,"epssPercentile":0.5274,"scores":{"cna":9.8,"vendor":7},"ingestedAt":"2026-09-14T15:23:07.450Z","slug":"CVE-2026-89662","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 42d7954b0a1907d4ef122aef94561952a033cdc3`\n- `Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a`\n- `Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < b8bad5a11416b26cc7fd4b18fba46d75ff636558`\n- `Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 1ce74d1b7770e69735e8f8e509807af4ff9c8ee7`\n- `Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < a6ead6fff3a7d03e49845f048f7000a2e0d34431`\n- `Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 4804c58f73a80d12df1de323bf97a164f6ee8743`\n- `Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 8cf4ff0a7c083dd5e0067f517d63979b74b66649`\n- `Linux >= 68ef3bc3166468678d5e1fdd216628c35bd1186f < 5e2fa29d223a9a1e6a948e40b109d09081d1decd`\n- `Linux e294c4c2d33b7307a89cdf31bec08a112d6a9297`\n- `Linux 797bfd05d4040fbf766198b3cfcc1838002cc890`\n- `Linux 0f44e9da465ea259b6c9f31a627f3c50a16e1679`\n- `Linux >= 4.9.91 < 4.10`\n- `Linux >= 4.14.31 < 4.15`\n- `Linux >= 4.15.14 < 4.16`\n- `Linux 4.16`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89662.json)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":223250,"id":"CVE-2026-89662","ts":1792180030831,"field":"cvss","old":"7","new":"9.8"},{"seq":223249,"id":"CVE-2026-89662","ts":1792180030831,"field":"severity","old":"high","new":"critical"},{"seq":203867,"id":"CVE-2026-89662","ts":1789490210416,"field":"cvss","old":"9.8","new":"7"},{"seq":203866,"id":"CVE-2026-89662","ts":1789490210416,"field":"severity","old":"critical","new":"high"},{"seq":197783,"id":"CVE-2026-89662","ts":1789384318834,"field":"cvss","old":"5.3","new":"9.8"},{"seq":197782,"id":"CVE-2026-89662","ts":1789384318834,"field":"severity","old":"medium","new":"critical"},{"seq":183707,"id":"CVE-2026-89662","ts":1789356677042,"field":"cvss","old":"9.8","new":"5.3"},{"seq":183706,"id":"CVE-2026-89662","ts":1789356677042,"field":"severity","old":"critical","new":"medium"},{"seq":153520,"id":"CVE-2026-89662","ts":1789285351126,"field":"cvss","old":null,"new":"9.8"},{"seq":153519,"id":"CVE-2026-89662","ts":1789285351126,"field":"severity","old":"none","new":"critical"},{"seq":147167,"id":"CVE-2026-89662","ts":1789270198309,"field":"cvss","old":null,"new":"5.3"},{"seq":147166,"id":"CVE-2026-89662","ts":1789270198309,"field":"severity","old":"none","new":"medium"},{"seq":108914,"id":"CVE-2026-89662","ts":1789183729520,"field":"cvss","old":null,"new":"5.3"},{"seq":108913,"id":"CVE-2026-89662","ts":1789183729520,"field":"severity","old":"none","new":"medium"}]}