CVE-2026-31430
Received Received - Intake
Out-of-Bounds Access in Linux Kernel X.509 Extension Parsing

Publication date: 2026-04-20

Last updated on: 2026-04-20

Assigner: kernel.org

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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Meta Information
Published
2026-04-20
Last Modified
2026-04-20
Generated
2026-05-07
AI Q&A
2026-04-20
EPSS Evaluated
2026-05-05
NVD
EUVD
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is an out-of-bounds access issue in the Linux kernel's X.509 certificate parsing code. Specifically, when parsing certificate extensions such as Basic Constraints or Key Usage that are empty, the code reads the first byte of the extension without first verifying the extension's length. This can lead to reading memory outside the intended bounds.

The flaw can be triggered by an unprivileged user who submits a specially crafted certificate to the kernel via the keyrings API.


How can this vulnerability impact me? :

The vulnerability allows an unprivileged user to cause an out-of-bounds memory access in the Linux kernel by submitting a specially crafted certificate. This could potentially lead to kernel crashes or other unpredictable behavior, which might be exploited for privilege escalation or denial of service.


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