CVE-2026-31685 netfilter: ip6t_eui64: reject invalid MAC header for all packets
A missing check in the Linux kernel's ip6t_eui64 module allows accessing an invalid MAC header, potentially causing a null pointer dereference and system crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-31685?
CVE-2026-31685 is a critical vulnerability in Linux kernel, published on 25 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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)`.
Weakness: CWE-125
Which versions are affected by CVE-2026-31685?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31685?
Apply the vendor's patch.
Is CVE-2026-31685 being exploited?
There is no known exploitation of CVE-2026-31685 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-84201, BELL-CVE-2026-31685, DEBIAN-CVE-2026-31685, GHSA-hf2p-g3jq-w2mx, ROOT-OS-DEBIAN-11-CVE-2026-31685, ROOT-OS-DEBIAN-12-CVE-2026-31685 and 3 more.