What is CVE-2025-39804?

CVE-2025-39804 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10, affecting Linux kernel versions from 6.16 onward and patched in 6.16.4 and 6.17. CVE-2025-39804 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-39804?

CVE-2025-39804 has a CVSS score of 7.8 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2025-39804?

Yes, CVE-2025-39804 has been patched. Fixed versions include 6.16.4 and 6.17. If you are running Linux kernel 6.16 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-39804 actively exploited?

CVE-2025-39804 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-39804

High

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.

Package Linux Kernel

Published 2025-09-15

Last modified 2025-11-24

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.8

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected versions

Linux kernel versions 6.16 and later are affected. Fixed in 6.16.4, 6.17 and their respective stable series.

Affected from

≥ 6.16

Fixed in

✓ 6.16.4 6.16.x ✓ 6.17

References

The following references provide additional information about CVE-2025-39804 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Kernel patch commit
https://git.kernel.org/stable/c/eec76ea5a7213c48529a46eed1b343e5cee3aaab
Patch
Kernel patch commit
https://git.kernel.org/stable/c/ef74efa598b7bbc5c24509f7f56af2806f81c339
Patch

Details

CVE ID CVE-2025-39804

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2025-09-15

Modified 2025-11-24

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-39804?

CVE-2025-39804 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 . It affects Linux kernel versions from 6.16 onward and has been patched in 6.16.4 and 6.17. CVE-2025-39804 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-39804?

CVE-2025-39804 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2025-39804?

Yes — CVE-2025-39804 has been patched. Fixed versions include 6.16.4 and 6.17. If you are running Linux kernel 6.16 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-39804 actively exploited?

No — CVE-2025-39804 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.