{"id":"CVE-2026-89686","title":"nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke\n\nnfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding\nfi_lock when the parent s…","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-416","CWE-476"],"vendor":"Linux","product":"Linux","affected":["Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < d12af460df27876661707efab3a8532146cb961f","Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < c517f27498757e616d2a8fe6d16caad1fee422e6","Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < 607a56fea772c1f4f4989d8e255dd4f7192d9604","Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < 97bda8b4284d90897a1f1922e5082ff9e35d7c7e","Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < ca94ba36172046be6a694a7986f6931e47ed4d51","Linux 4.0"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-16T19:26:03.140311Z"},"published":"2026-09-11","updated":"2026-10-21","sourceUpdated":"2026-10-21T12:48:21.196Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89686","references":[{"url":"https://git.kernel.org/stable/c/d12af460df27876661707efab3a8532146cb961f"},{"url":"https://git.kernel.org/stable/c/c517f27498757e616d2a8fe6d16caad1fee422e6"},{"url":"https://git.kernel.org/stable/c/607a56fea772c1f4f4989d8e255dd4f7192d9604"},{"url":"https://git.kernel.org/stable/c/97bda8b4284d90897a1f1922e5082ff9e35d7c7e"},{"url":"https://git.kernel.org/stable/c/ca94ba36172046be6a694a7986f6931e47ed4d51"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89686.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89686"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532098"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89686"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89686"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89686.mbox"},{"url":"https://kernelcve.org/list/?q=CVE-2026-89686"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00663,"epssPercentile":0.51482,"scores":{"cna":9.8,"vendor":5.3},"ingestedAt":"2026-09-14T15:23:07.473Z","slug":"CVE-2026-89686","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke\n\nnfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding\nfi_lock when the parent stateid is a delegation. A concurrent delegation\nrevoke via the laundromat can clear fi_deleg_file under fi_lock, causing\nnfsd_file_get() to return NULL and triggering the BUG_ON.\n\nThis race is client-reachable: two NFS clients can trigger it by having\none hold a delegation while another opens the same file to force a\nrecall. When the first client doesn't respond to the recall, the\nlaundromat revokes it. A concurrent LAYOUTGET from any client using the\ndelegation stateid hits the race window.\n\nFix this by taking fi_lock around the fi_deleg_file read in the\nSC_TYPE_DELEG path, matching the locking discipline of the\nfind_any_file() arm, and replacing the BUG_ON with a graceful error\nreturn that cleans up the partially-initialized layout stateid.\n\n## Affected\n\n- `Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < d12af460df27876661707efab3a8532146cb961f`\n- `Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < c517f27498757e616d2a8fe6d16caad1fee422e6`\n- `Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < 607a56fea772c1f4f4989d8e255dd4f7192d9604`\n- `Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < 97bda8b4284d90897a1f1922e5082ff9e35d7c7e`\n- `Linux >= c5c707f96fc9a6e5a57ca5baac892673270abe3d < ca94ba36172046be6a694a7986f6931e47ed4d51`\n- `Linux 4.0`\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 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-10-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89686.json)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":227214,"id":"CVE-2026-89686","ts":1792587296986,"field":"cvss","old":"5.3","new":"9.8"},{"seq":227213,"id":"CVE-2026-89686","ts":1792587296986,"field":"severity","old":"medium","new":"critical"},{"seq":226992,"id":"CVE-2026-89686","ts":1792584971768,"field":"cvss","old":"9.8","new":"5.3"},{"seq":226991,"id":"CVE-2026-89686","ts":1792584971768,"field":"severity","old":"critical","new":"medium"},{"seq":223242,"id":"CVE-2026-89686","ts":1792180028697,"field":"cvss","old":"7","new":"9.8"},{"seq":223241,"id":"CVE-2026-89686","ts":1792180028697,"field":"severity","old":"high","new":"critical"},{"seq":208464,"id":"CVE-2026-89686","ts":1790005708211,"field":"cvss","old":"5.3","new":"7"},{"seq":208463,"id":"CVE-2026-89686","ts":1790005708211,"field":"severity","old":"medium","new":"high"},{"seq":202995,"id":"CVE-2026-89686","ts":1789403733276,"field":"cvss","old":"9.8","new":"5.3"},{"seq":202994,"id":"CVE-2026-89686","ts":1789403733276,"field":"severity","old":"critical","new":"medium"},{"seq":197740,"id":"CVE-2026-89686","ts":1789384318642,"field":"cvss","old":"5.3","new":"9.8"},{"seq":197739,"id":"CVE-2026-89686","ts":1789384318642,"field":"severity","old":"medium","new":"critical"},{"seq":183677,"id":"CVE-2026-89686","ts":1789356676907,"field":"cvss","old":"9.8","new":"5.3"},{"seq":183676,"id":"CVE-2026-89686","ts":1789356676907,"field":"severity","old":"critical","new":"medium"},{"seq":153562,"id":"CVE-2026-89686","ts":1789285351293,"field":"cvss","old":null,"new":"9.8"},{"seq":153561,"id":"CVE-2026-89686","ts":1789285351293,"field":"severity","old":"none","new":"critical"},{"seq":147754,"id":"CVE-2026-89686","ts":1789270212161,"field":"cvss","old":null,"new":"5.3"},{"seq":147753,"id":"CVE-2026-89686","ts":1789270212161,"field":"severity","old":"none","new":"medium"},{"seq":109510,"id":"CVE-2026-89686","ts":1789183732222,"field":"cvss","old":null,"new":"5.3"},{"seq":109509,"id":"CVE-2026-89686","ts":1789183732222,"field":"severity","old":"none","new":"medium"}]}