Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-31685

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
25/04/2026
Last modified:
27/04/2026

Description

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> netfilter: ip6t_eui64: reject invalid MAC header for all packets<br /> <br /> `eui64_mt6()` derives a modified EUI-64 from the Ethernet source address<br /> and compares it with the low 64 bits of the IPv6 source address.<br /> <br /> The existing guard only rejects an invalid MAC header when<br /> `par-&gt;fragoff != 0`. For packets with `par-&gt;fragoff == 0`, `eui64_mt6()`<br /> can still reach `eth_hdr(skb)` even when the MAC header is not valid.<br /> <br /> Fix this by removing the `par-&gt;fragoff != 0` condition so that packets<br /> with an invalid MAC header are rejected before accessing `eth_hdr(skb)`.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H CVSS v3.1 Severity and Metrics:

Base Score: 9.40 CRITICAL
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): Low
Availability (A): High

Base Score 3.x
9.40
Severity 3.x
CRITICAL

References to Advisories, Solutions, and Tools