Cotonti through version 1.0.0 contains an open redirect vulnerability (CWE-601) in the cot_url_check() function. The function attempts to validate redirect destinations using a regular expression that does not anchor to the end of the string. As a result, an attacker can craft hostnames that begin with the legitimate site domain but redirect users to malicious, attacker-controlled hosts. This vulnerability can be exploited through the ratings plugin or other components that call the redirect functionality.

Successful exploitation allows attackers to redirect users to arbitrary external sites, potentially facilitating phishing or other social engineering attacks. The vulnerability impacts confidentiality and integrity to a limited extent but does not affect availability. The CVSS score of 6.1 reflects a medium severity with network attack vector, low attack complexity, no privileges required, user interaction required, and scope changed.

No official patch or fix is currently documented. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, users should be cautious about redirects originating from affected Cotonti installations and consider implementing additional validation or filtering on redirect URLs.