The Limit Login Attempts plugin for WordPress is vulnerable to Stored Cross-Site Scripting via its lock logging feature in versions up to, and including, 1.7.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever an administrator accesses the plugin's settings page. This only works when the plugin prioritizes use of the X-FORWARDED-FOR header, which can be configured in its settings.

The Limit Login Attempts WordPress plugin before 4.0.50 does not escape the IP addresses (which can be controlled by attacker via headers such as X-Forwarded-For) of attempted logins before outputting them in the reports table, leading to an Unauthenticated Stored Cross-Site Scripting issue.