CVE-2026-74671
In the Linux kernel, the following vulnerability has been resolved:
ima: fix out-of-bounds read in xattr_verify()
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.
CSIRTS triage
- What
- An out-of-bounds read in the IMA (Integrity Measurement Architecture) xattr_verify function can leak kernel memory.
- Who is affected
- Systems running affected Linux kernel versions with IMA extended attribute verification enabled.
- Urgency
- Low priority; CVSS 3.4 and not exploited but can leak small amounts of kernel memory through crafted extended attributes.
- Action
- Apply Linux kernel patch fixing array bounds checking in IMA xattr_verify function.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.18% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 7% of all EPSS-scored CVEs.
Advisory coverage (2)
- unknownCVE-2026-74671: In the Linux kernel, the following vulnerability has been resolved: ima: fix out-of-bounds rea…nvd · 2026-08-22
- lowCVE-2026-74671: ima: fix out-of-bounds read in xattr_verify()msrc · 2026-08-11
External references
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