CVE-2026-90418

What the bug is

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.

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

fs/nilfs2/page.c

What this is

NILFS2 FILESYSTEMMAINTAINERS section matched on fs/nilfs2/ · linux-nilfs@vger.kernel.org · Maintained

Kernel module

nilfs2

Check it on the machine

grep -w CONFIG_NILFS2_FS /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

lsmod | grep -w nilfs2

Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.

Show whether Debian builds this, per release

Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.

• bookworm, trixie, forky, sid, bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64

M

a module where it is built at all; some flavours do not build it

Build switch

CONFIG_NILFS2_FS

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages

Signals

Published

2026-09-17 (31 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.17%, higher than 5.7% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

fs/nilfs2

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
3.10	6.6.157	5166a21b12f5
3.10	6.12.110	4e1f21e7540b
3.10	6.18.52	3904fb0ee741
3.10	7.2.6	f181155baf0c
3.10	7.3	66f4ad3ce158

Debian advisories