CVE-2026-10513: Pfefferle Webmention

High severity, CVSS 7.2. EPSS: 0.4% chance of exploitation in the next 30 days.

The Webmention plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to and including 5.8.0 via parser-derived 'avatar' and 'url' author metadata. This is due to insufficient input sanitization and output escaping on user-supplied MF2 author properties processed by the unauthenticated webmention REST endpoint and rendered directly into HTML 'value' attributes by the edit-comment-form template without esc_attr() or esc_url(). This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a privileged user (moderator or administrator) opens the affected comment edit screen.

Affected products

• Pfefferle Webmention: up to and including 5.8.0

Published 2026-06-30. Last modified 2026-07-01.