What the vulnerability does
01Description
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.
Explanation of Vulnerability in Simple Terms
02Summary
Auto Thumbnails versions 1.0 and earlier contain a cross-site scripting vulnerability that allows authenticated users to inject malicious scripts. The vulnerability has a changed scope, meaning the impact can extend beyond the vulnerable component itself. Low-privileged users can exploit this without user interaction to compromise site integrity and access sensitive information.
What an attacker can do
03Attacker Capabilities
Inject malicious scripts that execute in other users' browsers and affect site functionality.
Potential impact on your site
04Site Impact
Authenticated users can inject scripts affecting other users and site operations; data exposure and defacement possible.
Conditions required to exploit
05Prerequisites
Attacker must have a low-privilege account on the site; no user interaction required.
Key dates
06Disclosure timeline
May 27, 2026
CVE published
May 27, 2026
Record updated
