CVE-2026-76579
LiteSpeed Cache <= 7.9 - Reflected Cross-Site Scripting via ESI 'esi' Parameter
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.
INFO
Published Date :
Sept. 19, 2026, 9:16 a.m.
Last Modified :
Sept. 19, 2026, 9:16 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update the LiteSpeed Cache plugin to the latest version.
- Sanitize all user inputs.
- Escape all outputs to prevent script injection.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-76579.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-76579 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-76579
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-76579 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-76579 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Sep. 19, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N Added CWE CWE-79 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/76xxx/CVE-2026-76579.json">CVE-2026-76579</a> Added Reference https://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L566 Added Reference https://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L591 Added Reference https://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L617 Added Reference https://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L855 Added Reference https://plugins.trac.wordpress.org/changeset/3676856/litespeed-cache/trunk/src/esi.cls.php Added Reference https://plugins.trac.wordpress.org/changeset?reponame=&new=3676856%40litespeed-cache%2Ftags%2F7.9.1&old=3635849%40litespeed-cache%2Ftags%2F7.9 Added Reference https://www.wordfence.com/threat-intel/vulnerabilities/id/ba236f86-0434-4030-8e14-4db3919226eb?source=cve