# 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-93268, DEBIAN-CVE-2026-93268, GHSA-7gm5-hpmg-j6v2, UBUNTU-CVE-2026-93268

## 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.

## Is CVE-2026-93268 being exploited?

There is no known exploitation of CVE-2026-93268 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93268 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-93268 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-93268/ (Markdown: https://insights.sbomify.com/CVE-2026-93268/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93268
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93268
- OSV: https://osv.dev/vulnerability/CVE-2026-93268

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93268/
Summaries are generated and may contain mistakes; the official description above is the record.