CVE-2026-90418 nilfs2: fix BUG in nilfs_copy_dirty_pages() on dirty state mismatch
A local attacker can trigger a kernel BUG in the nilfs2 filesystem by exploiting a dirty state mismatch, causing a system crash.
- 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-2026-90418?
CVE-2026-90418 is a denial of service vulnerability in Linux, published on 17 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:
nilfs2: fix BUG in nilfs_copy_dirty_pages() on dirty state mismatch
Syzbot reported a kernel BUG triggered within nilfs_copy_dirty_pages(), which copies dirty DAT file folios/pages to its shadow page cache. The BUG occurs when a retrieved dirty folio/page unexpectedly loses its 'dirty' status.
This issue arises because, since the commit referenced below, the 'dirty' flag of a folio/page can be cleared asynchronously after the filesystem detects metadata corruption and transitions to read-only mode.
Resolve the issue by returning an -EROFS error if the filesystem has transitioned to read-only mode. Also change the behavior to issue a kernel warning only once instead of triggering a kernel BUG when this unexpected 'dirty' state is detected while the filesystem is not in read-only mode.
Which versions are affected by CVE-2026-90418?
How do I fix CVE-2026-90418?
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-2026-90418 being exploited?
There is no known exploitation of CVE-2026-90418 in the wild and no public exploit code.
Sources
Also known as AZL-102522, BELL-CVE-2026-90418, DEBIAN-CVE-2026-90418, GHSA-c854-fhx8-wg6w, UBUNTU-CVE-2026-90418.