CVE-2026-76579: LiteSpeed Cache (WordPress plugin) · Cross-site Scripting
Affects LiteSpeed Cache (WordPress plugin)Source CVE Database V5
Not known to be exploited · CVSS 4.7 Medium.
Data as of 3 Nov 2026, 22:58 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 19 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| litespeedtechLiteSpeed Cache | Affected
| Fixed in– |
AI-suggested
Users should monitor the vendor's advisory for updates. Until a fix is available, avoid using untrusted input in the 'esi' parameter and consider disabling features that process this parameter if feasible. Implementing web application firewall (WAF) rules to detect and block suspicious 'esi' parameter usage may reduce risk.
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
- wordfence.com/threat-intel/vulnerabilities/id/ba236f86-0434-4030-8e14-4db3919226eb?source=cve (opens in a new tab)
- plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php (opens in a new tab)
- plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php (opens in a new tab)
- plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php (opens in a new tab)
- plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php (opens in a new tab)
- plugins.trac.wordpress.org/changeset?reponame=&new=3676856%40litespeed-cache%2Ftags%2F7.9.1&old=3635849%40litespeed-cache%2Ftags%2F7.9 (opens in a new tab)
- plugins.trac.wordpress.org/changeset/3676856/litespeed-cache/trunk/src/esi.cls.php (opens in a new tab)