SB2026040671 - Use-after-free in Linux kernel netfilter

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Main Vulnerability Database SB2026040671

SB2026040671 - Use-after-free in Linux kernel netfilter

Published: April 6, 2026

Security Bulletin ID SB2026040671
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 security vulnerability.


1) Use-after-free (CVE-ID: CVE-2026-23458)

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

The vulnerability exists due to use-after-free in ctnetlink_dump_exp_ct() and ctnetlink_exp_ct_dump_table() when handling multi-round netlink dump requests. A local user can trigger a netlink dump that spans multiple recvmsg() calls to cause a denial of service.

The issue occurs because a conntrack pointer stored in callback data is dereferenced after its reference is dropped, and the second dump round can access the freed object via nfct_help(ct). The proof of concept shows a slab-use-after-free read detected by KASAN.


Remediation

Install update from vendor's website.

References