CVE-2026-75944 in EOS
Summary
by MITRE • 09/15/2026
A race condition during supplicant re-authentication may leave a stale ACL entry that persists in the system. If the AclAgent subsequently restarts, this stale entry may be applied to new supplicants, resulting in incorrect access control enforcement. User interaction (an AclAgent restart by an administrator) is required for the unintended behavior to take effect.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described constitutes a race condition occurring within the supplicant re-authentication process of a network access control system. This specific timing flaw arises when multiple concurrent operations attempt to modify or update Access Control List entries during the transition phase of re-authentication. The core technical flaw lies in the lack of proper synchronization mechanisms between the authentication subsystem and the policy enforcement agent, known as AclAgent. When a supplicant device attempts to re-establish its connection credentials, the system fails to atomically handle the removal or update of existing access rules before applying new ones. This oversight allows for a window where stale ACL entries remain in memory even after they should have been invalidated by the successful completion of the re-authentication handshake. The persistence of these outdated policy definitions represents a significant deviation from expected state management protocols, leading to inconsistencies between the intended security posture and the actual enforcement configuration.
The operational impact of this vulnerability is primarily tied to the lifecycle events of the AclAgent process itself. Under normal circumstances, if the agent restarts cleanly without prior race conditions, it would typically rebuild its policy database based on current supplicant states. However, due to the presence of stale ACL entries left behind by the race condition, a subsequent restart causes these incorrect rules to be loaded and applied to new or re-authenticating supplicants. This results in incorrect access control enforcement, where devices may receive network permissions they are not authorized for, or conversely, legitimate users might be denied appropriate access levels. The severity of this issue is somewhat mitigated by the requirement for user interaction; specifically, an administrator must manually restart the AclAgent service to trigger the application of these stale rules. This dependency on administrative action reduces the likelihood of automated exploitation but does not eliminate the risk during routine maintenance or troubleshooting scenarios where such restarts are common practice.
From a classification perspective, this vulnerability aligns with CWE-362, which defines race conditions involving concurrent access and updates to a shared resource without adequate locking or synchronization. The failure to ensure atomicity in updating ACL entries allows one thread of execution to read stale data while another is modifying it, leading to unpredictable system behavior. Furthermore, the exploitation vector relates to ATT&CK technique T1078, Valid Accounts, as an attacker could potentially leverage this misconfiguration to gain unauthorized network access if they can influence or predict when a supplicant re-authenticates and subsequently trigger an agent restart. Although direct remote code execution is not implied, the ability to manipulate network segmentation policies through race conditions poses a serious threat to network integrity and compliance with security frameworks that mandate strict adherence to defined access control lists.
Mitigation strategies for this vulnerability should focus on both immediate remediation and long-term architectural improvements. Administrators should ensure that all software patches addressing this specific race condition are applied promptly, as vendors typically release updates that introduce proper locking mechanisms or transactional integrity checks during the re-authentication process. In environments where patching is delayed, operational procedures can be adjusted to minimize risk; for instance, avoiding unnecessary restarts of the AclAgent service and ensuring that any planned maintenance windows include a thorough verification of ACL states before bringing services back online. Additionally, implementing monitoring alerts for unexpected agent restarts or anomalies in supplicant authentication logs can help detect potential exploitation attempts early. Long-term solutions involve refactoring the codebase to enforce strict state consistency checks, ensuring that no stale entries persist beyond their validity period regardless of service interruptions. This includes adopting atomic operations for policy updates and validating ACL integrity during every startup sequence to prevent legacy or orphaned rules from influencing current network access decisions.