CVE-2009-1030: WordPress Mu

Medium severity, CVSS 4.3. EPSS: 4.7% chance of exploitation in the next 30 days.

Cross-site scripting (XSS) vulnerability in the choose_primary_blog function in wp-includes/wpmu-functions.php in WordPress MU (WPMU) before 2.7 allows remote attackers to inject arbitrary web script or HTML via the HTTP Host header.

Affected products

• WordPress WordPress Mu: up to and including 2.6; version 1.0 only; version 1.1 only; version 1.1.1 only; version 1.2 only; version 1.2.1 only; …

Published 2009-03-20. Last modified 2026-06-16.