The WooCommerce Additional Fees On Checkout (Free) plugin for WordPress suffers from a reflected cross-site scripting vulnerability (CWE-79) due to improper neutralization of input in the 'number' parameter. This allows unauthenticated attackers to inject malicious scripts that execute in the context of a victim's browser when they interact with a crafted URL. The vulnerability affects all versions up to 1.4.7. The CVSS 3.1 base score is 6.1, reflecting network attack vector, low attack complexity, no privileges required, user interaction required, and impacts confidentiality and integrity with no availability impact. There is no indication of known exploits in the wild or an available patch at this time.

Successful exploitation can lead to execution of arbitrary scripts in the context of the victim's browser, potentially allowing theft of sensitive information or session tokens, and manipulation of web content. The impact is limited to confidentiality and integrity, with no direct availability impact. The vulnerability requires user interaction (clicking a malicious link) and does not require authentication.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, users should exercise caution with untrusted links that interact with the affected plugin. Monitoring vendor channels for updates is recommended.