Vulnerability · Published May 27, 2026 · Assigned by Wordfence
CVE-2026-8899Auto Thumbnails <= 1.0 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode Attributes
Medium 6.4
In plain English
A medium-severity cross-site scripting in Auto Thumbnails from gapgag55. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| gapgag55 | Auto Thumbnails | 0 – through 1.0 |
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N