CVE-2026-76579 json
LiteSpeed Cache <= 7.9 - Reflected Cross-Site Scripting via ESI 'esi' Parameter
published 2026-09-19 50 d ago modified 2026-09-21 48 d ago also EUVD-2026-83568
- cvss
- 4.7
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 31%
- public exploits
- 0
- none known
Summary
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.
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 50 d ago
Exploit prediction
0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 4.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N |
Affected products
- litespeedtech LiteSpeed Cache
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
- wordfence.com /threat-intel/vulnerabilities/id/ba236f86-0434-4030-8e14-4db3919226eb?source=cve
- plugins.trac.wordpress.org /browser/litespeed-cache/tags/7.9/src/esi.cls.php#L855
- plugins.trac.wordpress.org /browser/litespeed-cache/tags/7.9/src/esi.cls.php#L617
- plugins.trac.wordpress.org /browser/litespeed-cache/tags/7.9/src/esi.cls.php#L591
- plugins.trac.wordpress.org /browser/litespeed-cache/tags/7.9/src/esi.cls.php#L566
- plugins.trac.wordpress.org /changeset?reponame=&new=3676856%40litespeed-cache%2Ftags%2F7.9.1&old=3635849%40litespeed-cache%2Ftags%2F7.9
- plugins.trac.wordpress.org /changeset/3676856/litespeed-cache/trunk/src/esi.cls.php
Sources
- CVE List CVE-2026-76579
- NVD CVE-2026-76579
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