CVE-2026-93873

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 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.

Vulnerability in Cotonti is an open redirect in cot_url_check() using a regex without 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.

Cotonti through 1.0.0 derives password recovery validation tokens from md5(microtime()) in users.passrecover.php, creating a predictable token space of approximately one million values per second. Unauthenticated attackers can read the server Date header, precompute candidate tokens within a narrow time window, and probe them against the passrecover authentication endpoint to reset any account password including administrators.

Cotonti 1.0.0 is vulnerable to stored Cross-Site Scripting in the Personal File Storage (PFS) module. A folder title (pff_title) is imported with the 'TXT' filter, which does not strip or encode HTML (the tag check in cot_import is disabled), so an authenticated user can store HTML/JavaScript in a folder title.

Cotonti 1.0.0 is vulnerable to Cross-Site Request Forgery in the Personal File Storage (PFS) module. In modules/pfs/inc/pfs.editfolder.php, the folder update action ('a=update') updates folder metadata without calling cot_check_xg to validate the anti-CSRF token.

Cotonti 1.0.0 is vulnerable to Cross-Site Request Forgery in the Personal File Storage (PFS) module. The file upload action ('a=upload') processes uploaded files without calling cot_check_xg to validate the anti-CSRF token, even though sibling actions such as 'delete' do.