CVE-2026-4351

The Perfmatters plugin for WordPress is vulnerable to arbitrary file overwrite via path traversal in all versions up to, and including, 2.5.9. This is due to the PMCS::action_handler() method processing the bulk action activate/deactivate handlers without any authorization check or nonce verification. The $_GET['snippets'][] values are passed unsanitized to Snippet::activate()/Snippet::deactivate() which call Snippet::update() then file_put_contents() with the traversed path. This makes it possible for authenticated attackers, with Subscriber-level access and above, to overwrite arbitrary files on the server with a fixed PHP docblock content, potentially causing denial of service by corrupting critical files like .htaccess or index.php.