CVE-2026-52990: Linux kernel · fsnotify: fix inode reference leak in fsnotify_recalc_mask()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in b740cc86816bbc87902ae9db74cd21abde3c8d63 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 14:05 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in b740cc86816bbc87902ae9db74cd21abde3c8d63, 926ec3937b28d30c08427053c8d8af7f9e086d82, 8c8afa6444e6bdc145d2bf2f3aeeca6da3e36b42 +4
Exploitation evidence
Disclosed: evidence found.
CVE published 24 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in– |
Description
In the Linux kernel, the following vulnerability has been resolved: fsnotify: fix inode reference leak in fsnotify_recalc_mask() fsnotify_recalc_mask() fails to handle the return value of __fsnotify_recalc_mask(), which may return an inode pointer that needs to be released via fsnotify_drop_object() when the connector's HAS_IREF flag transitions from set to cleared. This manifests as a hung task with the following call trace: INFO: task umount:1234 blocked for more than 120 seconds. Call Trace: __schedule schedule fsnotify_sb_delete generic_shutdown_super kill_anon_super cleanup_mnt task_work_run do_exit do_group_exit The race window that triggers the iref leak: Thread A (adding mark) Thread B (removing mark) ────────────────────── ──────────────────────── fsnotify_add_mark_locked(): fsnotify_add_mark_list(): spin_lock(conn->lock) add mark_B(evictable) to list spin_unlock(conn->lock) return /* ---- gap: no lock held ---- */ fsnotify_detach_mark(mark_A): spin_lock(mark_A->lock) clear ATTACHED flag on mark_A spin_unlock(mark_A->lock) fsnotify_put_mark(mark_A) fsnotify_recalc_mask(): spin_lock(conn->lock) __fsnotify_recalc_mask(): /* mark_A skipped: ATTACHED cleared */ /* only mark_B(evictable) remains */ want_iref = false has_iref = true /* not yet cleared */ -> HAS_IREF transitions true -> false -> returns inode pointer spin_unlock(conn->lock) /* BUG: return value discarded! * iput() and fsnotify_put_sb_watched_objects() * are never called */ Fix this by deferring the transition true -> false of HAS_IREF flag from fsnotify_recalc_mask() (Thread A) to fsnotify_put_mark() (thread B).
References
- git.kernel.org/stable/c/926ec3937b28d30c08427053c8d8af7f9e086d82 (opens in a new tab)
- git.kernel.org/stable/c/8c8afa6444e6bdc145d2bf2f3aeeca6da3e36b42 (opens in a new tab)
- git.kernel.org/stable/c/b740cc86816bbc87902ae9db74cd21abde3c8d63 (opens in a new tab)
- git.kernel.org/stable/c/5c80289503da3658e3df80280598c68d181eadbd (opens in a new tab)
- git.kernel.org/stable/c/4aca914ac152f5d055ddcb36704d1e539ac08977 (opens in a new tab)