CVE-2026-64040

What the bug is

When vfs_mkdir() fails, the error code is not extracted from the returned error pointer. This causes mkdir_error to be reached with ret=0, which leads to returning ERR_PTR(0) (NULL) instead of a proper error pointer. Fix this by extracting the error code from the error pointer when vfs_mkdir() fails.

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/cachefiles/namei.c

What this is

CACHEFILES: FS-CACHE BACKEND FOR CACHING ON MOUNTED FILESYSTEMSMAINTAINERS section matched on fs/cachefiles/ · netfs@lists.linux.dev · Supported

Kernel module

cachefiles

Check it on the machine

grep -w CONFIG_CACHEFILES /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 cachefiles

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, sidm

m

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

Build switch

CONFIG_CACHEFILES

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

2026-07-19 (3 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.16%, higher than 4.7% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

unimportantsource

Subsystem

fs/cachefiles

Upstream fixes

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

Introduced	Fixed in	Commit
6.15	6.18.57	86f4c1586418
6.15	7.0.11	0940108d27c6
6.15	7.1	8a220d1c312c