CVE-2026-72457 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
apparmor: fail policy unpack on accept2 allocation failure
unpack_pdb() may need to allocate a missing ACCEPT2 table for older policy data. If that allocation failed, it set an error message but jumped to the success path, returning a policydb with the required table missing.
Return -ENOMEM through the normal failure path when the ACCEPT2 allocation fails. Remove the now-unused out label.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability resides in the Linux kernel's AppArmor security module, specifically within the policy database unpacking functionality that handles legacy policy data formats. The issue manifests when the system encounters older AppArmor policies that require conversion to newer internal representations during loading or unpacking operations. The vulnerability represents a critical logic flaw in error handling and resource management within the security subsystem.
The technical flaw occurs within the unpack_pdb() function which processes AppArmor policy databases and attempts to allocate memory for missing ACCEPT2 tables when dealing with older policy versions. When this memory allocation fails due to insufficient resources, the code incorrectly sets an error message but then continues execution by jumping to what appears to be a success path rather than properly handling the allocation failure. This results in a malformed policy database being returned to the calling functions with critical components missing from the internal data structures. The vulnerability is classified as a memory management error and aligns with CWE-704, which deals with incorrect handling of resource allocation failures.
The operational impact of this vulnerability extends beyond simple resource exhaustion scenarios, potentially allowing attackers to manipulate AppArmor policy loading behavior in ways that could compromise system security boundaries. When the ACCEPT2 table allocation fails, the system continues processing with incomplete policy data, which could lead to unexpected access control decisions or create denial-of-service conditions within the security module itself. This issue particularly affects systems running older AppArmor policies that require conversion to newer formats, and represents a failure in proper error propagation mechanisms. The vulnerability demonstrates how improper error handling in security-critical code paths can lead to inconsistent states where system protections are weakened.
Mitigation strategies should focus on ensuring proper error propagation through the standard kernel failure paths rather than using goto statements that bypass normal error handling mechanisms. System administrators should update to patched kernel versions that properly return -ENOMEM errors when ACCEPT2 table allocations fail, and ensure all AppArmor policies are compatible with current kernel versions. The fix involves removing the unused out label and modifying the control flow to follow standard kernel error handling patterns where allocation failures result in proper error codes being propagated up the call stack. Organizations should also implement monitoring for unusual AppArmor policy loading behavior and maintain updated security patches across their Linux infrastructure to prevent exploitation of such memory management vulnerabilities that could undermine system integrity controls.