CVE-2026-8899

Description

The Auto Thumbnail plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the -thumbnails- shortcode in all versions up to, and including, 1.0. This is due to insufficient input sanitization and output escaping on the shortcode-s -width- and -height- attributes in the athn_thumbnails() function, which are concatenated directly into an HTML <img> tag. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.