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CVE-2026-31430

7.1 · HIGH

In the Linux kernel, the following vulnerability has been resolved: X.509: Fix out-of-bounds access when parsing extensions Leo reports an out-of-bounds access when parsing a certificate with emp…

Published Apr 20, 2026linuxCWE-125EPSS 0.08%

Overview

CVE-2026-31430 is a high-severity vulnerability affecting linux linux_kernel. It was published on April 20, 2026 and has a CVSS 3.1 base score of 7.1 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

X.509: Fix out-of-bounds access when parsing extensions

Leo reports an out-of-bounds access when parsing a certificate with

empty Basic Constraints or Key Usage extension because the first byte of

the extension is read before checking its length. Fix it.

The bug can be triggered by an unprivileged user by submitting a

specially crafted certificate to the kernel through the keyrings(7) API.

Leo has demonstrated this with a proof-of-concept program responsibly

disclosed off-list.

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

VendorProductVersionsStatus
linuxlinux_kernel>= 6.4, < 6.6.135Affected

References

Refgit.kernel.org/stable/c/206121294b9cf27f0589857f80d64f87e496ffb2Refgit.kernel.org/stable/c/30ab358fad0c7daa1d282ec48089901b21b36a20Refgit.kernel.org/stable/c/672b526def1f94c1be8eb11b885b803da0d8c2f1Refgit.kernel.org/stable/c/7fb4dadc2734f4020d7543d688b8d49c8e569c61Refgit.kernel.org/stable/c/d702c3408213bb12bd570bb97204d8340d141c51

How CyberStrike helps

Frequently asked questions

What is CVE-2026-31430?

CVE-2026-31430 is a high-severity vulnerability affecting linux linux_kernel. It was published on April 20, 2026 and has a CVSS 3.1 base score of 7.1 (HIGH).

How severe is CVE-2026-31430?

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-31430?

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-2026-31430?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-31430 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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