CVE-2026-72377

What the bug is

Regular AFS files correctly use afs_file_aops which have release_folio set as netfs_release_folio, so AS_RELEASE_ALWAYS is valid for them when fscache is enabled (set via afs_vnode_set_cache()). Symlinks and mountpoints in AFS use afs_dir_aops, which does not provide a release_folio callback. However, afs_apply_status() unconditionally calls mapping_set_release_always() for these. In such case when memory management code attempts to release folios, filemap_release_folio() checks folio_needs_release() which returns true due to AS_RELEASE_ALWAYS being set. Since there is no release_folio callback, it falls through to try_to_free_buffers(), which at present expects buffer_heads to be not null. For symlinks and mountpoints without buffer_heads, this causes pointer dereference. [dh: Added more bits that were missed]

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/afs/inode.c
fs/afs/internal.h

What this is

AFS FILESYSTEMMAINTAINERS section matched on fs/afs/ · linux-afs@lists.infradead.org · Supported

Kernel module

kafs

Check it on the machine

grep -w CONFIG_AFS_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 kafs

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, sidMnot 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_AFS_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

2026-08-15 (2 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.20%, higher than 8.9% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

unimportantsource

Subsystem

fs/afs

Upstream fixes

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

Introduced	Fixed in	Commit
6.14	7.1.5	9d6b0f6d437e
6.14	7.2	81e985b4c3a6