CVE-2026-31685
Linux Kernel vulnerability
- Published25 Apr 2026
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6t_eui64: reject invalid MAC header for all packets `eui64_mt6()` derives a modified EUI-64 from the Ethernet source address and compares it with the low 64 bits of the IPv6 source address. The existing guard only rejects an invalid MAC header when `par->fragoff != 0`. For packets with `par->fragoff == 0`, `eui64_mt6()` can still reach `eth_hdr(skb)` even when the MAC header is not valid. Fix this by removing the `par->fragoff != 0` condition so that packets with an invalid MAC header are rejected before accessing `eth_hdr(skb)`.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:HAffected products
Remediation
- https://git.kernel.org/stable/c/288138418bef956f8b295751a4536c60f0e89f4a
- https://git.kernel.org/stable/c/309ae3e9a51a69699ca94eac5fac5688fa562d55
- https://git.kernel.org/stable/c/807d6ee15804df6f01a35c910f09612e858739a6
- https://git.kernel.org/stable/c/9eda5478746ef7dc0e4e537b5a5e4b0ca1027091
- https://git.kernel.org/stable/c/fdce0b3590f724540795b874b4c8850c90e6b0a8
References
- https://git.kernel.org/stable/c/288138418bef956f8b295751a4536c60f0e89f4a
- https://git.kernel.org/stable/c/309ae3e9a51a69699ca94eac5fac5688fa562d55
- https://git.kernel.org/stable/c/4d75bc2cd093bf5803edf512c099bfb220fd6459
- https://git.kernel.org/stable/c/7d6a57411caf54df025860c9b1a82cd42d57a562
- https://git.kernel.org/stable/c/807d6ee15804df6f01a35c910f09612e858739a6
- https://git.kernel.org/stable/c/9eda5478746ef7dc0e4e537b5a5e4b0ca1027091
- https://git.kernel.org/stable/c/d5603591373441fecf9951833d6d873e09320f08
- https://git.kernel.org/stable/c/fdce0b3590f724540795b874b4c8850c90e6b0a8
Frequently asked
Is CVE-2026-31685 being actively exploited?
CVE-2026-31685 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.34%.
How severe is CVE-2026-31685?
CVE-2026-31685 has a CVSS 3.1 base score of 9.4, rated critical. EPSS estimates a 0.34% probability of exploitation.
Which products are affected by CVE-2026-31685?
Affected products include Linux Kernel.
How do I fix CVE-2026-31685?
Upgrade affected software to a fixed version, for example Linux Kernel 6.6.136 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-31685 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.