CVE-2025-61581 in Traffic Control
Summary
by MITRE • 10/16/2025
** UNSUPPORTED WHEN ASSIGNED ** Inefficient Regular Expression Complexity vulnerability in Apache Traffic Control.
This issue affects Apache Traffic Control: all versions.
People with access to the management interface of the Traffic Router component could specify malicious patterns and cause unavailability.
As this project is retired, we do not plan to release a version that fixes this issue. Users are recommended to find an alternative or restrict access to the instance to trusted users.
NOTE: This vulnerability only affects products that are no longer supported by the maintainer.
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Analysis
by VulDB Data Team • 10/16/2025
The vulnerability identified as CVE-2025-61581 represents a critical inefficient regular expression complexity issue within Apache Traffic Control's Traffic Router component. This weakness falls under the category of CWE-1333 which specifically addresses inefficient regular expression complexity, making it a significant concern for systems that rely on pattern matching for routing decisions. The vulnerability exists in all versions of the Apache Traffic Control software, indicating a fundamental flaw in the regular expression handling mechanism that has persisted across the entire product lifecycle.
The technical flaw manifests when users with access to the management interface of the Traffic Router component can submit malicious regular expression patterns that cause excessive computational overhead during pattern matching operations. This creates a potential denial of service condition where legitimate requests cannot be processed due to the system becoming overwhelmed by the resource-intensive regular expression evaluation. The vulnerability specifically targets the Traffic Router's pattern matching capabilities, which are essential for directing traffic to appropriate backend servers based on configured routing rules. Attackers can exploit this by crafting complex regular expressions that trigger catastrophic backtracking behaviors, consuming excessive CPU cycles and memory resources.
The operational impact of this vulnerability is severe for organizations that continue to operate unsupported Apache Traffic Control instances. The issue can lead to complete service unavailability as the system becomes unable to process legitimate routing requests. This affects not only the immediate functionality of traffic routing but can also impact downstream applications and services that depend on proper traffic management. The vulnerability's exploitation requires only access to the management interface, making it particularly dangerous in environments where administrative privileges are not properly restricted. Organizations using this retired software face a critical security risk that cannot be remediated through standard patching procedures.
Security practitioners should note that this vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and specifically addresses the pattern matching weaknesses that can lead to resource exhaustion. Given that Apache Traffic Control is no longer maintained by its developers, organizations must implement immediate compensating controls to mitigate this risk. The recommended mitigation strategy involves restricting access to the management interface to only trusted users and implementing strict access controls through network segmentation. Additionally, organizations should consider migrating to supported alternatives that provide proper regular expression handling and security updates. The vulnerability serves as a stark reminder of the risks associated with operating unsupported software in production environments, where security gaps can remain unaddressed for extended periods.