Apache Traffic Control: ReDoS issue in Traffic Router configuration

Vulnerability

Description

CVE-2025-61581 is an Inefficient Regular Expression Complexity (ReDoS) vulnerability in Apache Traffic Control, affecting all versions of the CDN management software. The flaw resides in the Traffic Router component, where the regular expression engine processes user-supplied patterns without adequate bounds checks. By crafting a malicious regular expression pattern, an authenticated user can cause the regex engine to exhibit catastrophic backtracking, resulting in excessive CPU consumption and unavailability of the Traffic Router service [1][2].

Exploitation

The attack requires an authenticated user with access to the management interface of the Traffic Router component. There is no requirement for network-level attack; the attacker must be able to submit patterns through the web-based management API or GUI. Once submitted, the vulnerable regex engine processes the pattern, leading to a denial of service condition. No other authentication bypass or privilege escalation is needed [1][2].

Impact

A successful exploit leads to unavailability of the Traffic Router component. Since Traffic Router is responsible for DNS and HTTP redirection to the nearest CDN cache, its unavailability can disrupt content delivery to end users, effectively causing a denial of service for the entire CDN service. The vulnerability does not expose data or allow code execution [1][2].

Remediation

Apache Traffic Control is a retired project (marked as UNSUPPORTED WHEN ASSIGNED), and the maintainers have announced they will not release a fix. Users are advised to either migrate to an alternative CDN management solution or restrict access to the Traffic Router management interface to only highly trusted users [1][2][3]. No workaround or patch is available from the Apache project.