EWWW Image Optimizer <= 8.7.3 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'data-script' Lazy Load Attribute in Post Content

Summary

The EWWW Image Optimizer plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'data-script' Lazy Load Attribute in Post Content in all versions up to, and including, 8.7.3 due to insufficient input sanitization and output escaping. 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. The exploit is achieved by embedding a crafted img element with class='lazyload' and a data-script attribute pointing to an attacker-controlled URL in post content, which the plugin's bundled lazysizes ls.unveilhooks addon then uses to dynamically create and insert a script element into the DOM at page view time.

Timeline

1. Aug 19, 2026, 6:37 AM UTCCVE published
2. Aug 20, 2026, 1:35 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Aug 20, 2026, 3:26 PM UTCRecord last updated

Affected versions

• nosilver4u EWWW Image Optimizer

  through 8.7.3

References 10