CVE-2026-80892

What the bug is

fs/erofs/decompressor_lzma.c sizes the module-global MicroLZMA stream pool from num_possible_cpus() when the lzma_streams module parameter is unset, then z_erofs_load_lzma_config() preallocates one image-supplied dictionary per stream, accepting dictionaries up to 8 MiB. On high-CPU systems, a small EROFS image can pin hundreds of MiB of vmalloc-backed decoder state until the erofs module is unloaded. Impact: An EROFS image mounted by the system can pin up to 8 MiB of vmalloc memory per LZMA stream, either as intended or unexpectedly. Bound the default stream count by a new CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS option, default 16, so the worst-case default preallocation is 128 MiB if the number of CPUs is no less than 16 while preserving the existing per-image dictionary limit. An explicit lzma_streams module parameter is still honoured as-is, so administrators who deliberately size the pool are not affected.

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/erofs/Kconfig
fs/erofs/decompressor_lzma.c

What this is

EROFS FILE SYSTEMMAINTAINERS section matched on fs/erofs/ · linux-erofs@lists.ozlabs.org · Maintained

Kernel module

erofs

Check it on the machine

grep -wE 'CONFIG_EROFS_FS|CONFIG_EROFS_FS_ZIP_LZMA' /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 erofs

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 does not build this code in 1 release. It does build it in 4 releases, so the answer depends on which release the machine runs.

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

n

not enabled on any flavour - this release does not build the code

m

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

Build switches

CONFIG_EROFS_FS, CONFIG_EROFS_FS_ZIP_LZMA

Reads as

all on means the file is compiled; any one off means it is not.

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

2026-09-04 (44 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.17%, higher than 6.2% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

fs/erofs

Upstream fixes

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

Introduced	Fixed in	Commit
5.16	6.1.184	682cb3ece37f
5.16	6.6.151	e8b3d09aa888
5.16	6.12.103	0c676903cb2a
5.16	6.18.44	5aaa06dfc10f
5.16	7.1.8	e52da169b8c0
5.16	7.2	c9b47e6b2311

Debian advisories