Critical Linux Kernel Netfilter Vulnerability Scores 9.4 CVSS

Last refreshed2026-10-15

Status: UPDATED | Advisory ID: CVE-2026-31685

Key Details

CVE	CVE-2026-31685
CVSS Score / Version	9.4 (Critical) / CVSS v3.1
Updated	2026-10-15
CVSS Vector	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H`
CVSS Prose	attack vector is network; attack complexity is low; privileges required is none; user interaction is none; scope is unchanged; confidentiality impact is high; integrity impact is low; availability impact is high.
Affected products	Linux Kernel and Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Exploitation prediction (EPSS)	0.39% probability of exploitation in the next 30 days (31% percentile) -- FIRST.org's EPSS model.

Vendor	Product	Affected Versions	Patch Status
Linux	Linux Kernel
Siemens	SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Vendor

Product

Affected Versions

Patch Status

Linux

Linux Kernel

Siemens

SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Subsystems	Controllers & Field I/O, OT Supporting Infrastructure
Sectors	All Sectors

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)`. (NVD)

Monitor Linux's and Siemens's web pages for any future patch releases.

Source	Reference
NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-31685
CVE	https://www.cve.org/CVERecord?id=CVE-2026-31685

Source

Reference

NVD

CVE