SB20260816121 - Always-Incorrect Control Flow Implementation in Linux kernel netfilter



SB20260816121 - Always-Incorrect Control Flow Implementation in Linux kernel netfilter

Published: August 16, 2026

Security Bulletin ID SB20260816121
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Local access
Highest impact Denial of service

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Always-Incorrect Control Flow Implementation (CVE-ID: CVE-2026-72256)

CWE-ID: CWE-670 - Always-Incorrect Control Flow Implementation

CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to improper handling of template conntrack state in xt_cluster_mt() in the netfilter xt_cluster matcher when processing packets associated with a template conntrack. A local user can trigger packet processing that reaches xt_cluster_hash() with incomplete conntrack state to cause a denial of service.

The issue occurs when the raw table CT target attaches a template conntrack to skb->_nfct before normal conntrack processing.


Remediation

Install update from vendor's website.