CVE-2026-31685: Linux kernel · Out-of-bounds Read
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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
- git.kernel.org/stable/c/4d75bc2cd093bf5803edf512c099bfb220fd6459 (opens in a new tab)
- git.kernel.org/stable/c/7d6a57411caf54df025860c9b1a82cd42d57a562 (opens in a new tab)
- git.kernel.org/stable/c/d5603591373441fecf9951833d6d873e09320f08 (opens in a new tab)
- git.kernel.org/stable/c/288138418bef956f8b295751a4536c60f0e89f4a (opens in a new tab)
- git.kernel.org/stable/c/9eda5478746ef7dc0e4e537b5a5e4b0ca1027091 (opens in a new tab)
- git.kernel.org/stable/c/807d6ee15804df6f01a35c910f09612e858739a6 (opens in a new tab)
- git.kernel.org/stable/c/309ae3e9a51a69699ca94eac5fac5688fa562d55 (opens in a new tab)
- git.kernel.org/stable/c/fdce0b3590f724540795b874b4c8850c90e6b0a8 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)