CVE-2026-93268 ext4: skip extra isize expansion during mount to prevent deadlock
A deadlock in the Linux kernel ext4 filesystem during mount can cause a denial of service, requiring a kernel patch.
- 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-2026-93268?
CVE-2026-93268 is a denial of service vulnerability in Linux, published on 24 Sep 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:
ext4: skip extra isize expansion during mount to prevent deadlock
ext4_try_to_expand_extra_isize() is called from __ext4_mark_inode_dirty() while holding an active jbd2 handle. During mount (!SB_ACTIVE), the expand path may move xattrs to external blocks and release ea_inodes via iput(). When !SB_ACTIVE, iput() calls write_inode_now() which acquires s_writepages_rwsem, creating a circular lock dependency:
s_writepages_rwsem --> jbd2_handle --> xattr_sem --> s_writepages_rwsem
This can be triggered via:
ext4_process_orphan() -> ext4_truncate() -> ext4_mark_inode_dirty() -> ext4_try_to_expand_extra_isize()
or:
ext4_evict_inode() -> ext4_mark_inode_dirty() -> ext4_try_to_expand_extra_isize()
Skip expansion when !SB_ACTIVE. This is a minor loss of functionality (extra isize won't grow for these inodes during mount), which e2fsck can resolve later if needed.
Which versions are affected by CVE-2026-93268?
How do I fix CVE-2026-93268?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-93268 being exploited?
There is no known exploitation of CVE-2026-93268 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-93268, DEBIAN-CVE-2026-93268, GHSA-7gm5-hpmg-j6v2, UBUNTU-CVE-2026-93268.