CVE-2025-39802

lib/crypto: arm/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

Using Linux by Linux?

Get instant alerts when new vulnerabilities affect Linux - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
HIGH7.8
Exploit prediction
EPSS 0.3%

Description

In the Linux kernel, the following vulnerability has been resolved: lib/crypto: arm/poly1305: Fix register corruption in no-SIMD contexts Restore the SIMD usability check that was removed by commit 773426f4771b ("crypto: arm/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.

All versions6.16 ≤ v < 6.16.46.16773426f4771bdd82ac5c834bf4c1775315c73a46
Vendor states this is fixed in 52c3e242f4d0043186b70d65460ba1767f27494a (fixed)
Vendor states this is fixed in 87bdfba903be7084cb3ee04032b14a81181fe413 (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/52c3e242f4d0043186b70d65460ba1767f27494a
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/87bdfba903be7084cb3ee04032b14a81181fe413

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

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card