VulnerabilityPublished 20 Apr 2026Updated 5 Nov 2026

CVE-2026-31430: Linux kernel · X.509: Fix out-of-bounds access when parsing extensions

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in d702c3408213bb12bd570bb97204d8340d141c51 : update Linux kernel when convenient.

Data as of 5 Nov 2026, 22:04 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in d702c3408213bb12bd570bb97204d8340d141c51, 206121294b9cf27f0589857f80d64f87e496ffb2, 672b526def1f94c1be8eb11b885b803da0d8c2f1 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 20 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 30eae2b037af54b24109dcaea21db46f6285c69b, < d702c3408213bb12bd570bb97204d8340d141c51	Fixed in d702c3408213bb12bd570bb97204d8340d141c51
LinuxLinux	Affected ≥ 30eae2b037af54b24109dcaea21db46f6285c69b, < 206121294b9cf27f0589857f80d64f87e496ffb2	Fixed in 206121294b9cf27f0589857f80d64f87e496ffb2
LinuxLinux	Affected ≥ 30eae2b037af54b24109dcaea21db46f6285c69b, < 672b526def1f94c1be8eb11b885b803da0d8c2f1	Fixed in 672b526def1f94c1be8eb11b885b803da0d8c2f1
LinuxLinux	Affected ≥ 30eae2b037af54b24109dcaea21db46f6285c69b, < 30ab358fad0c7daa1d282ec48089901b21b36a20	Fixed in 30ab358fad0c7daa1d282ec48089901b21b36a20
LinuxLinux	Affected ≥ 30eae2b037af54b24109dcaea21db46f6285c69b, < 7fb4dadc2734f4020d7543d688b8d49c8e569c61	Fixed in 7fb4dadc2734f4020d7543d688b8d49c8e569c61
LinuxLinux	Affected =6.4	Fixed in–

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.

References

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