The Customer Email Verification for WooCommerce plugin for WordPress is vulnerable to Privilege Escalation via the `alg_wc_ev_verify_email` parameter in versions up to, and including, 3.3.0

Overview

The Customer Email Verification for WooCommerce plugin for WordPress is vulnerable to Privilege Escalation via the alg_wc_ev_verify_email parameter in versions up to, and including, 3.3.0. The vulnerability exists because alg_wc_ev_generate_user_code() generates the per-user activation secret using wp_rand(100) when the plugin's 'Encoding method' is set to 'hashids', producing only ~101 possible values (~7 bits of entropy); the resulting token is a reversible Hashids encoding with no cryptographic MAC, and the unauthenticated verify() handler — hooked to init at PHP_INT_MAX with no nonce check and no rate limiting — accepts and acts on the attacker-controlled ?alg_wc_ev_verify_email= GET parameter directly. This makes it possible for unauthenticated attackers to gain authentication as any unverified WordPress account, including administrator-level accounts, by brute-forcing the trivially small activation code space via a forged verification URL. Exploitation requires that the 'Encoding method' setting be changed to 'hashids' (non-default), that the attacker recover or brute-force the Hashids salt (which defaults to an md5(time()) value set at first initialization), and that the target account's email address remain unverified.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.