CVE-2026-72459
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
apparmor: aa_label_alloc use aa_label_free on alloc failure
aa_label_alloc() allocates a secid before allocating or taking the label proxy. If the later proxy step fails, the error path only freed the label memory, leaking any resources initialized by aa_label_init().
Use aa_label_free() on the failure path so partially initialized labels release their secid and other label resources before the backing memory is freed.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability resides within the Linux kernel's AppArmor security module, specifically addressing a resource management flaw in the label allocation process that could lead to system instability and potential security implications. The issue occurs during the aa_label_alloc() function execution where the system first allocates a security identifier before proceeding with label proxy allocation. When subsequent proxy allocation fails, the error handling code only releases the label memory itself while leaving other resources initialized by aa_label_init() in an inconsistent state.
The technical flaw manifests as a resource leak pattern where partially constructed label objects retain their security identifier and associated resources even though the overall allocation process has failed. This improper cleanup behavior violates fundamental resource management principles and can result in accumulation of leaked resources over time, potentially leading to system performance degradation or memory exhaustion. The vulnerability represents a classic case of incomplete error handling where the failure path does not properly reverse the initialization sequence that occurred prior to the allocation failure.
The operational impact of this vulnerability extends beyond simple resource consumption issues as it creates potential security implications within the kernel's mandatory access control framework. When AppArmor label allocations fail, the leaked security identifiers and associated resources may remain accessible to malicious processes or could interfere with subsequent legitimate allocation requests. This inconsistency in resource management could potentially be exploited to undermine the integrity of the security module's access control decisions, particularly in environments where AppArmor policies are heavily utilized for system protection.
The fix implemented addresses this issue by ensuring that aa_label_free() is called on the error path rather than only freeing the label memory directly. This approach guarantees that all resources initialized by aa_label_init() are properly released before the backing memory is freed, maintaining consistency in the resource management state and preventing the accumulation of partially initialized label objects. This remediation aligns with established security practices for kernel module development and follows the principle of least privilege by ensuring proper cleanup even during error conditions.
This vulnerability classification falls under CWE-459 which specifically addresses incomplete cleanup issues in software systems, particularly where partial initialization leads to resource leaks or inconsistent states. The fix demonstrates adherence to secure coding practices recommended in both NIST SP 800-163 and the Linux kernel security guidelines that emphasize proper error handling and resource management throughout all execution paths. From an ATT&CK perspective, this vulnerability could potentially be leveraged by adversaries seeking to perform resource exhaustion attacks or to create persistent access points through compromised kernel components, making it a significant concern for system administrators maintaining security-sensitive environments.
The resolution of this issue represents a critical improvement in kernel stability and security posture, particularly for systems relying heavily on AppArmor for mandatory access control. By ensuring complete cleanup during error conditions, the fix prevents potential cascading failures that could occur from accumulated resource leaks while maintaining the integrity of the security module's access control mechanisms. This type of vulnerability is particularly concerning in enterprise environments where kernel-level security modules are extensively utilized to protect against both internal and external threats through comprehensive access control policies.