{"id":"CVE-2026-89682","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89682","summary":"nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net\n\nnfsd_file_dispose_list_delayed() defers fput() to nfsd service threads\nvia a per-net freeme queue, preventing the shrinker and GC worker from\nbearing the cost of closing files (see ffb402596147).  However, the\nqueue lives in a separately-allocated struct nfsd_fcache_disposal that\nis freed by nfsd_free_fcache_disposal_net() during per-net teardown.\nThe global shrinker, laundrette, and fsnotify callbacks can still be\ninside nfsd_file_dispose_list_delayed() dereferencing that pointer,\ncausing a use-after-free.\n\nInline the spinlock and freeme list directly into struct nfsd_net (as\nfcache_dispose_lock and fcache_dispose_list), eliminating the separately\nallocated struct nfsd_fcache_disposal entirely.  These fields now have\nthe same lifetime as the net namespace itself, so there is no dangling\npointer to chase.\n\nnfsd_file_cache_start_net() now just initializes the inline fields and\ncannot fail due to allocation.  nfsd_file_cache_shutdown_net() drains\nthe inline list directly instead of freeing a separate struct.  The\nalloc/free helpers are removed.","published":"2026-09-11T19:46:04.882Z","modified":"2026-09-14T03:46:24.810878816Z","cvss":{"score":8.1,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.18.51"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/ba0ee9e04b7a0356c28d5a2fe445db675d24e572"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cadc9036d5a8209f89e7026ddba7cfb1c716b03c"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89682.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89682"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-14T03:46:24.810878816Z"}}