CVE-2026-31430

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.

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EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/206121294b9cf27f0589857f80d64f87e496ffb2 https://git.kernel.org/stable/c/30ab358fad0c7daa1d282ec48089901b21b36a20 https://git.kernel.org/stable/c/672b526def1f94c1be8eb11b885b803da0d8c2f1 https://git.kernel.org/stable/c/7fb4dadc2734f4020d7543d688b8d49c8e569c61 https://git.kernel.org/stable/c/d702c3408213bb12bd570bb97204d8340d141c51

Frequently Asked Questions

What is CVE-2026-31430? +

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.

How do I check if I'm vulnerable to CVE-2026-31430? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.