SB2026050232 - Use-after-free in Linux kernel netfilter

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Main Vulnerability Database SB2026050232

SB2026050232 - Use-after-free in Linux kernel netfilter

Published: May 2, 2026

Security Bulletin ID SB2026050232
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) Use-after-free (CVE-ID: CVE-2026-43027)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 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/E:U/U:Clear


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

The vulnerability exists due to a use-after-free in nf_conntrack_helper_unregister and expectation handling in netfilter nf_conntrack_helper when unregistering a helper while stale expectations remain. A local user can trigger helper unregistration and subsequent expectation access to cause a denial of service.

The issue is triggered because expectations referencing the helper survive cleanup and are later dereferenced during expectation dumps or packet-driven conntrack initialization.


Remediation

Install update from vendor's website.

References