{"id":"CVE-2026-89686","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89686","summary":"nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke","details":"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 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.","published":"2026-09-11T19:46:07.877Z","modified":"2026-09-14T03:46:25.911061255Z","cvss":{"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"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.12.109"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/607a56fea772c1f4f4989d8e255dd4f7192d9604"},{"type":"WEB","url":"https://git.kernel.org/stable/c/97bda8b4284d90897a1f1922e5082ff9e35d7c7e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c517f27498757e616d2a8fe6d16caad1fee422e6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ca94ba36172046be6a694a7986f6931e47ed4d51"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89686.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89686"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-14T03:46:25.911061255Z"}}