CVE-2025-39804
7.5 · HIGHOverview
CVE-2025-39804 is a high-severity vulnerability affecting linux linux_kernel. It was published on September 15, 2025 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| linux | linux_kernel | >= 6.16, < 6.16.4 | Affected |
Frequently Asked Questions
What is CVE-2025-39804?
CVE-2025-39804 is a high-severity vulnerability affecting linux linux_kernel. It was published on September 15, 2025 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2025-39804?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2025-39804?
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2025-39804?
CyberStrike's AI-powered security agents can automatically detect CVE-2025-39804 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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