SB2026040156 - Out-of-bounds write in Linux kernel apparmor

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Main Vulnerability Database SB2026040156

SB2026040156 - Out-of-bounds write in Linux kernel apparmor

Published: April 1, 2026

Security Bulletin ID SB2026040156
Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Local access
Highest impact Code execution

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 security vulnerability.


1) Out-of-bounds write (CVE-ID: CVE-2026-23406)

The vulnerability allows a local user to cause a denial of service or potentially execute arbitrary code.

The vulnerability exists due to improper pointer arithmetic in the AppArmor match_char() macro within the Linux kernel's DFA matching logic when processing path permissions during file open operations. A local user can provide a specially crafted file access request that triggers differential encoding chain traversal with a post-incremented string pointer, causing the pointer to advance multiple times per iteration and resulting in out-of-bounds memory reads. This can lead to kernel memory corruption and system instability.

The vulnerability is exploitable during AppArmor policy enforcement when opening files, and may allow privilege escalation or system crash.


Remediation

Install update from vendor's website.

References