The Broken Link Checker WordPress plugin before 2.4.2 does not validate a the link URLs before making a request to them, which could allow admin users to perform SSRF attack, for example on a multisite installation.

A vulnerability was found in Broken Link Checker Plugin up to 1.10.1 on WordPress. It has been declared as problematic. Affected by this vulnerability is the function optionspage of the file core/core.php of the component Settings Page. The manipulation of the argument exclusionlist/blccustomfields leads to cross site scripting. The attack can be launched remotely. Upgrading to version 1.10.2 is able to address this issue. The patch is named 90615fe9b0b6f9e6fb254d503c302e53a202e561. It is recommended to upgrade the affected component. The associated identifier of this vulnerability is VDB-230659.

The Broken Link Checker WordPress plugin before 1.11.20 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfilteredhtml capability is disallowed (for example in multisite setup)

A reflected XSS vulnerability was found in includes/admin/table-printer.php in the broken-link-checker (aka Broken Link Checker) plugin 1.11.8 for WordPress. This allows unauthorized users to inject client-side JavaScript into an admin-only WordPress page via the wp-admin/tools.php?page=view-broken-links sfilter parameter in a search action.

The broken-link-checker plugin through 1.11.8 for WordPress (aka Broken Link Checker) is susceptible to Reflected XSS due to improper encoding and insertion of an HTTP GET parameter into HTML. The filter function on the page listing all detected broken links can be exploited by providing an XSS payload in the sfilter GET parameter in a filterid=search request. NOTE: this is an end-of-life product.