CVE-2026-78471: optimizingmatters autoptimize Cross-site Scripting

Vulnerability summary

CVE-2026-78471 is a medium (CVSS 5.4) Cross-site Scripting vulnerability in optimizingmatters autoptimize. EPSS estimates a 0.22% chance of exploitation in the next 30 days, higher than 11.8% of scored vulnerabilities. Fixed in 3.1.16.

Timeline

1. 02-10-2026
   PublishedVulnerability first disclosed.
2. 03-10-2026
   Last modifiedVulnerability information updated.

Description

The Autoptimize plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Author Name in all versions up to, and including, 3.1.15.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Exploitation requires an administrator to have enabled Autoptimize's 'Lazy-load images?' option, the w3-total-cache/w3-total-cache.php file to be present on disk with the plugin disabled, a class named Minify_HTML to be loaded into scope by another plugin, and the malicious comment to be approved by a moderator before the payload renders.

• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.