CVE-2026-31685 CRITICAL

CVE-2026-31685: netfilter: ip6t_eui64: reject invalid MAC header for all packets

Vendor Linux
Product Linux
Published April 25, 2026
Last update June 1, 2026

CVSS base score

9.4/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H

What the vulnerability does

01Description

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)`.

Key dates

02Disclosure timeline

April 25, 2026 CVE published
June 1, 2026 Record updated