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VulnerabilityPublished Updated

CVE-2026-31685: Linux kernel · Out-of-bounds Read

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 9.4 Critical · fixed in fdce0b3590f724540795b874b4c8850c90e6b0a8 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 14:18 UTC

CVSS 3.1 base score
9.4Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers can reliably automate steps 1–4 of the kill chain
Technical impact
Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in fdce0b3590f724540795b874b4c8850c90e6b0a8, d5603591373441fecf9951833d6d873e09320f08, 288138418bef956f8b295751a4536c60f0e89f4a +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < fdce0b3590f724540795b874b4c8850c90e6b0a8
Fixed in
  • fdce0b3590f724540795b874b4c8850c90e6b0a8
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < d5603591373441fecf9951833d6d873e09320f08
Fixed in
  • d5603591373441fecf9951833d6d873e09320f08
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 288138418bef956f8b295751a4536c60f0e89f4a
Fixed in
  • 288138418bef956f8b295751a4536c60f0e89f4a
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 807d6ee15804df6f01a35c910f09612e858739a6
Fixed in
  • 807d6ee15804df6f01a35c910f09612e858739a6
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 309ae3e9a51a69699ca94eac5fac5688fa562d55
Fixed in
  • 309ae3e9a51a69699ca94eac5fac5688fa562d55
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 9eda5478746ef7dc0e4e537b5a5e4b0ca1027091
Fixed in
  • 9eda5478746ef7dc0e4e537b5a5e4b0ca1027091

AI-suggested

A fix for this vulnerability is available and has been applied in multiple Linux kernel commits as listed in the established facts. Users and administrators should update their Linux kernel to a version including these fixes to mitigate the vulnerability. No additional mitigation steps are indicated by the vendor advisory.

Description

CVE-2026-31685 is a critical vulnerability in the Linux kernel's netfilter ip6t_eui64 module. The flaw involves improper validation of the MAC header in IPv6 packets, allowing packets with invalid MAC headers to be processed under certain conditions. This occurs because the check rejecting invalid MAC headers was only applied when the fragment offset was non-zero, leaving packets with zero fragment offset vulnerable. The issue has been fixed by removing this condition, ensuring all packets with invalid MAC headers are rejected before accessing the Ethernet header.

References

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