CVE-2026-80638 ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent
An out-of-bounds write in the OCFS2 filesystem allows attackers to cause a kernel panic or potentially execute code via crafted file operations.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80638?
CVE-2026-80638 is a high-severity memory corruption vulnerability in Linux, published on 28 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent
[BUG] Unlinking a refcounted file whose refcount tree has leaf blocks triggers a fortify panic due to an out-of-bounds write.
[CAUSE] When the last leaf block is removed from a refcount tree, ocfs2_remove_refcount_extent() converts the root back to leaf mode with a bulk memset on &rb->rf_records. rf_records sits in an anonymous union with rf_list. rf_list.l_tree_depth aliases rf_records.rl_count, and is 0 for a single-level tree. With rl_count equal to 0, the memset writes past the 16-byte declared size of rf_records, which the fortify checker catches.
[FIX] Replace the bulk memset on &rb->rf_records with a correctly-bounded memset on rl_recs[] alone, after setting rl_count to the correct value.
Which versions are affected by CVE-2026-80638?
How do I fix CVE-2026-80638?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-80638 being exploited?
There is no known exploitation of CVE-2026-80638 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-80638, GHSA-pf3v-qrvc-chw5, UBUNTU-CVE-2026-80638.