Broken Link Checker < 2.4.12 - Unauthenticated RCE via Query Variable Injection

Description

The plugin does not limit which query variables it accepts from user input on sites using plain permalinks, allowing unauthenticated users to overwrite arbitrary PHP global variables, and to execute arbitrary code on the server when a classic (non-block) theme is active.

Plain permalinks are the default for single-site WordPress installations.