Relevanssi <= 4.28.1 - Reflected Cross-Site Scripting

Summary

The Relevanssi – A Better Search plugin for WordPress is vulnerable to Reflected Cross-Site Scripting in versions up to, and including, 4.28.1 via the 's', 'post_types', and 'orderby' request parameters. This is due to insufficient input sanitization and output escaping in the relevanssi_debug_array() function in lib/debug.php, which dumps user-supplied query variables through print_r() inside a <pre> block without HTML escaping. The debug path is enabled by supplying the relevanssi_debug=on request parameter when the administrator has previously enabled the 'Debugging mode' setting; the gate itself is a configuration check with no capability, nonce, or logged-in check (the vendor explicitly suppresses nonce verification on that line). This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a specially crafted link.

Timeline

1. Sep 11, 2026, 3:39 AM UTCCVE published
2. Sep 11, 2026, 2:09 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Sep 11, 2026, 2:10 PM UTCRecord last updated

Affected versions

• comesio Relevanssi – A Better Search

  through 4.28.1

References 12