CVE-2026-74671

What the bug is

The digest-length check in xattr_verify() mixes int and size_t: if (xattr_len - sizeof(xattr_value->type) - hash_start >= iint->ima_hash->length) sizeof() yields size_t, so the usual arithmetic conversions promote the whole left-hand side to unsigned 64-bit before the subtraction runs. For a truncated xattr this underflows instead of going negative: a 1-byte IMA_XATTR_DIGEST_NG xattr (xattr_len == 1, hash_start == 1) turns "1 - 1 - 1" into SIZE_MAX, which is trivially >= ima_hash->length. The check then passes and the following memcmp() reads iint->ima_hash->length bytes starting past the end of the buffer vfs_getxattr_alloc() allocated for it. Nothing upstream clamps xattr_len back into a safe range first: ima_get_hash_algo() only special-cases xattr_len < 2 to pick a default algorithm, and evm_verifyxattr() returns INTEGRITY_UNKNOWN rather than failing when no HMAC key is loaded, so a truncated security.ima value reaches the length check as-is. Rewrite the comparison so every operand stays a signed int and no implicit conversion to size_t can occur.

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.

security/integrity/ima/ima_appraise.c

What this is

INTEGRITY MEASUREMENT ARCHITECTURE (IMA)MAINTAINERS section matched on security/integrity/ima/ · linux-integrity@vger.kernel.org · Supported

Check it on the machine

grep -wE 'CONFIG_IMA|CONFIG_IMA_APPRAISE|CONFIG_INTEGRITY' /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.

Show whether Debian builds this, per release

Debian builds this code. Every release below compiles the affected file into the kernels it ships.

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

y

built into the kernel image on every flavour - only a patch removes it

Build switches

CONFIG_IMA, CONFIG_IMA_APPRAISE, CONFIG_INTEGRITY

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

2026-08-22 (2 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.18%, higher than 6.8% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

security/integrity

Upstream fixes

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

Introduced	Fixed in	Commit
3.13	5.10.265	d823b5f45570
3.13	5.15.216	caeb105c15ea
3.13	6.1.183	a784b4732ac7
3.13	6.6.152	b6cb134707a2
3.13	6.12.104	7e515b6c9aab
3.13	6.18.45	27f392406159
3.13	7.1.9	dd04114af0d4
3.13	7.2	5ff232d31106

Debian advisories