Cotonti through 1.0.0 contains an open redirect vulnerability in the cot_url_check() function that validates redirect destinations using a regular expression lacking an end-of-string anchor. Attackers can bypass the redirect guard by supplying hostnames beginning with the site domain to redirect users to attacker-controlled hosts through the ratings plugin or other redirect callers.
https://github.com/Cotonti/Cotonti/pull/1899
https://github.com/Cotonti/Cotonti/issues/1891
https://github.com/Cotonti/Cotonti/blob/1.0.0/system/functions.php
https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/ratings/ratings.ajax.php
Published: 2026-09-18
Updated: 2026-09-18
Base Score: 6.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N
Severity: Medium
Base Score: 6.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Severity: Medium
Base Score: 5.3
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
Severity: Medium
EPSS: 0.00217