CVE-2026-100521

Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize() without allowed_classes restriction, allowing unauthenticated attackers to instantiate arbitrary PHP classes with attacker-controlled properties. Attackers can exploit PHP object injection through crafted serialized payloads to trigger gadget chains and achieve database manipulation or code execution.

Cotonti 1.0.0 (master branch, commit f43f1fc3) is vulnerable to Cross-Site Request Forgery in the administration rights handler. In system/admin/admin.rights.php, the rights update action ('a=update') modifies group access rights (including via cot_auth_add_group) without calling cot_check_xg to validate the anti-CSRF token.

Cotonti through 1.0.0 contains a cross-site request forgery vulnerability in admin.users.php that allows attackers to delete user groups without token verification. Attackers can craft malicious links or pages that trick authenticated administrators into deleting custom groups and their associated permissions by riding the administrator's session.

Cotonti through version 1.0.0 contains a cross-site request forgery vulnerability in the extensions manager that allows attackers to perform state-changing actions without anti-CSRF token validation. Attackers can craft links or embed images to force administrators to install, update, pause, or unpause extensions by tricking them into visiting a malicious page while authenticated.

Cotonti through version 1.0.0 contains an open redirect vulnerability in message.php that base64-decodes the redirect parameter without domain validation. Unauthenticated attackers can craft malicious links with encoded external URLs to redirect users to arbitrary sites via meta refresh tags for phishing attacks.

Cotonti through version 1.0.0 contains a reflected cross-site scripting vulnerability in message.php where the lng parameter is not properly escaped before output in the confirmation dialog. Unauthenticated attackers can craft malicious links with script payloads in the lng parameter to execute arbitrary JavaScript in victim browser sessions.

Vulnerability in Cotonti fails to validate anti-CSRF tokens in the contact plugin submission handler, allowing attackers to forge messages attributed to authenticated victims and send them to the administrator inbox.

Cotonti 1.0.0 passes the base64-decoded cb parameter to unserialize() without allowed_classes restriction in the comments plugin EditAction. Registered users with comment write permissions can instantiate arbitrary PHP objects and potentially achieve file write or code execution through gadget chains.

Vulnerability in Cotonti fails to validate redirect destinations in page bodies prefixed with redir:, allowing authenticated users with page creation or edit permissions to store redirects to arbitrary external hosts, which can be used for phishing.

Vulnerability in Cotonti fails to validate anti-CSRF tokens in the ratings plugin AJAX handler, allowing attackers to forge ratings on behalf of authenticated users. Malicious pages can auto-submit POST requests to modify stored rating data.