CVE-2026-66745 describes a session fixation vulnerability in Artica Proxy before version 4.50.000000 Service Pack 7. The flaw allows an unauthenticated attacker to pre-set a session identifier (PHPSESSID) on a victim's browser. When the victim authenticates via fw.login.php, the attacker gains control of the authenticated administrative session on port 9000. This enables unauthorized administrative access without needing to compromise credentials. The vulnerability is addressed in hotfix 20260724-02.

An attacker can hijack administrative sessions by forcing a victim to use a session identifier controlled by the attacker. This leads to unauthorized administrative access to the Artica Proxy management interface on port 9000, potentially allowing full control over the proxy configuration and operations. The vulnerability requires user interaction (victim login) and has a high attack complexity due to the need to set the session beforehand.

A fix is available in hotfix 20260724-02, which addresses this session fixation vulnerability. Users should apply this hotfix or upgrade to Service Pack 7 or later to remediate the issue. Until patched, administrators should be aware of the risk of session fixation and consider additional protections such as monitoring for suspicious session activity.