The Blog Filter plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'AWL-BlogFilter' shortcode in versions up to, and including, 1.5.3 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
https://plugins.trac.wordpress.org/changeset/2974261/blog-filter#file54
https://plugins.trac.wordpress.org/browser/blog-filter/tags/1.5.3/blog-filter-output.php#L128