CVE-2026-90318

What the bug is

fat_scan_logstart() leaves the matching directory entry's buffer head in sinfo.bh for the caller to release, just like fat_scan(). fat_rebuild_parent() uses the directory entry to rebuild the parent inode for the nostale_ro NFS export path, but does not release sinfo.bh after a successful scan. Release it once fat_build_inode() has consumed the directory entry data.

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/fat/nfs.c

What this is

VFAT/FAT/MSDOS FILESYSTEMMAINTAINERS section matched on fs/fat/ · Maintained

Kernel module

fat

Check it on the machine

grep -w CONFIG_FAT_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 fat

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 as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.

• bookworm, trixie, forky, sid, bookworm · linux-6.12m

m

a loadable module on every flavour - check lsmod, can be blacklisted

Build switch

CONFIG_FAT_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

0.21%, higher than 10.6% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

fs/fat

Upstream fixes

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

Introduced	Fixed in	Commit
3.10	5.10.270	5e44b6944e11
3.10	5.15.221	d2a86329152c
3.10	6.1.188	0f18d712ba9c
3.10	6.6.157	e38587d98d1c
3.10	6.12.110	c6a67aa43817
3.10	6.18.52	571ea4263d69
3.10	7.2.6	7565e4450763
3.10	7.3	83e98dbf19ab

Debian advisories