CVE-2026-31430: Linux Kernel

High severity, CVSS 7.1. EPSS: 0.1% chance of exploitation in the next 30 days.

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.

Affected products

• Linux Linux Kernel: from 6.4, before 6.6.135 (fixed in 6.6.135); from 6.7, before 6.12.82 (fixed in 6.12.82); from 6.13, before 6.18.23 (fixed in 6.18.23); from 6.19, before 6.19.13 (fixed in 6.19.13); version 7.0 only

Published 2026-04-20. Last modified 2026-06-17.