CVE-2025-39804

lib/crypto: arm64/poly1305: Fix register corruption in no-SIMD contexts

HIGH
7.8
CVSS Score
Published: September 15, 2025 at 12:36 PM UTC
Updated: October 19, 2026 at 09:10 PM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
HIGH7.8
Exploit prediction
EPSS 0.3%

Description

In the Linux kernel, the following vulnerability has been resolved: lib/crypto: arm64/poly1305: Fix register corruption in no-SIMD contexts Restore the SIMD usability check that was removed by commit a59e5468a921 ("crypto: arm64/poly1305 - Add block-only interface"). This safety check is cheap and is well worth eliminating a footgun. While the Poly1305 functions should not be called when SIMD registers are unusable, if they are anyway, they should just do the right thing instead of corrupting random tasks' registers and/or computing incorrect MACs. Fixing this is also needed for poly1305_kunit to pass. Just use may_use_simd() instead of the original crypto_simd_usable(), since poly1305_kunit won't rely on crypto_simd_disabled_for_test.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

6.16 ≤ v < 6.16.46.16a59e5468a921937cb7317892779c67046ad9f5cc
Vendor states this is fixed in eec76ea5a7213c48529a46eed1b343e5cee3aaab (fixed)
Vendor states this is fixed in ef74efa598b7bbc5c24509f7f56af2806f81c339 (fixed)
Vendor states this is fixed in 6.16 (unaffected)
Vendor states this is fixed in 6.16.4 (unaffected)
Vendor states this is fixed in 6.17 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (2)

Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/eec76ea5a7213c48529a46eed1b343e5cee3aaab
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/ef74efa598b7bbc5c24509f7f56af2806f81c339

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
NVD-CWE-noinfo

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