CVE-2026-53129
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
A use-after-free vulnerability was found in the Linux kernel's mbcache mechanism. The mb_cache_destroy() function fails to cancel the pending c_shrink_work work item before freeing memory, potentially leading to access of already freed memory.
Risk Assessment
The risk involves potential kernel code execution by a privileged user (root or CAP_SYS_ADMIN) when unmounting ext2/ext4/ocfs2 filesystems, which could lead to system crash or privilege escalation.
Recommendation
Immediately update the Linux kernel to a version containing the fix that adds cancel_work_sync() before shrinker_free() in mb_cache_destroy().
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: fs/mbcache: cancel shrink work before destroying the cache mb_cache_destroy() calls shrinker_free() and then frees all cache entries and the cache itself, but it does not cancel the pending c_shrink_work work item first. If mb_cache_entry_create() schedules c_shrink_work via schedule_work() and the work item is still pending or running when mb_cache_destroy() runs, mb_cache_shrink_worker() will access the cache after its memory has been freed, causing a use-after-free. This is only reachable by a privileged user (root or CAP_SYS_ADMIN) who can trigger the last put of a mounted ext2/ext4/ocfs2 filesystem. Cancel the work item with cancel_work_sync() before calling shrinker_free(), ensuring the worker has finished and will not be rescheduled before the cache is torn down.