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.

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No vendor mitigations ingested yet for this CVE. The mitigation-content worker queues fetches as references arrive — check back in a few minutes, or see the references list below.

References

• https://www.wordfence.com/threat-intel/vulnerabilities/id/f0cc349a-96f9-4b11-a0b4-28bc4ccc022c?source=cve
• https://plugins.trac.wordpress.org/browser/automatic-thumbnail/tags/1.0/index.php#L34
• https://plugins.trac.wordpress.org/browser/automatic-thumbnail/tags/1.0/index.php#L13

CWEs

CWE-79

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