CVE-2026-52990
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
In the Linux kernel, an inode reference leak occurs in fsnotify_recalc_mask() because the return value of __fsnotify_recalc_mask() (an inode pointer) is discarded, preventing iput() and fsnotify_put_sb_watched_objects() from being called. This leads to a hung task during filesystem unmount.
Risk Assessment
The inode reference leak can cause the umount process to hang for over 120 seconds, preventing proper filesystem unmount and potentially leading to service unavailability or requiring a system reboot.
Recommendation
Apply the Linux kernel patch that moves the HAS_IREF flag transition from fsnotify_recalc_mask() to fsnotify_put_mark() to ensure proper inode release. Update to a kernel version containing this fix.
Other vulnerabilities in Linux kernel
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- CVE-2026-80542Unknown
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- CVE-2026-80535Unknown
In the Linux kernel XFS filesystem, during directory tree repair, a self-referential directory may be detected. In such a case, the repair code attempts to lock the same inode twice (double iolock/ilock), leading to a deadlock. The fix detects this corner case and handles it appropriately.
Original NVD description (English source)
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).