CVE-2026-98245 btrfs: take commit root semaphore when iterating in mark_block_group_to_copy()
A use-after-free in the Linux kernel btrfs filesystem allows local attackers to execute code or escalate privileges via concurrent transaction commits.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98245?
CVE-2026-98245 is an use after free vulnerability in Linux, published on 6 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
btrfs: take commit root semaphore when iterating in mark_block_group_to_copy()
mark_block_group_to_copy() iterates over the commit root with skip_locking=true. A concurrent transaction commit can swap and free the commit root during iteration, causing use-after-free when accessing extent buffers.
Fix it by using path->need_commit_sem to protect the commit root search.
Which versions are affected by CVE-2026-98245?
How do I fix CVE-2026-98245?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-98245 being exploited?
There is no known exploitation of CVE-2026-98245 in the wild and no public exploit code.
Sources
Also known as AZL-105984, BELL-CVE-2026-98245, DEBIAN-CVE-2026-98245, GHSA-crm6-8p5c-4rv5, UBUNTU-CVE-2026-98245.