CVE-2026-76579

Description

The LiteSpeed Cache plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'esi' parameter in all versions up to, and including, 7.9 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. Exploitation requires that the attacker supply a validly signed 'esi' value in the GET query string while submitting a separate attacker-controlled 'esi' payload as a POST body field, relying on PHP's default $_REQUEST merge order to have the POST value take precedence at the point of execution.

References

https://www.wordfence.com/threat-intel/vulnerabilities/id/ba236f86-0434-4030-8e14-4db3919226eb?source=cve

https://plugins.trac.wordpress.org/changeset?reponame=&new=3676856%40litespeed-cache%2Ftags%2F7.9.1&old=3635849%40litespeed-cache%2Ftags%2F7.9

https://plugins.trac.wordpress.org/changeset/3676856/litespeed-cache/trunk/src/esi.cls.php

https://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L855

https://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L617

https://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L591

https://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L566

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

EPSS