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.
CVE-2026-76579
MEDIUMPre-NVD 4.74.7—Trending — 4 sources updated this week
EchelonGraph scoreHIGH confidence
Score 4.7 from GitHub Security Advisory published 2026-09-19. a secondary CVSS source baseline 4.7; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
4.7EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.7Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 4.7
- EG Score
- 4.7(high)
- EG Risk
- 21(Track)EG Risk 21/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity47% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 29%
- KEV
- Not listed
Published
September 19, 2026
Last Modified
September 21, 2026
References (7)
- security@wordfencehttps://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L566
- security@wordfencehttps://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L591
- security@wordfencehttps://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L617
- security@wordfencehttps://plugins.trac.wordpress.org/browser/litespeed-cache/tags/7.9/src/esi.cls.php#L855
- security@wordfencehttps://plugins.trac.wordpress.org/changeset/3676856/litespeed-cache/trunk/src/esi.cls.php
- security@wordfencehttps://plugins.trac.wordpress.org/changeset?reponame=&new=3676856%40litespeed-cache%2Ftags%2F7.9.1&old=3635849%40litespeed-cache%2Ftags%2F7.9
- security@wordfencehttps://www.wordfence.com/threat-intel/vulnerabilities/id/ba236f86-0434-4030-8e14-4db3919226eb?source=cve
Vendor Advisories for CVE-2026-76579(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 22× in last 7d / 22× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-09-24 15:04 UTCEG score recompute
- 2026-09-24 15:04 UTCGHSA enrichment
- 2026-09-24 14:04 UTCEPSS rescore
- 2026-09-23 17:54 UTCEPSS rescore
- 2026-09-23 14:33 UTCEG score recompute
- 2026-09-23 14:32 UTCGHSA enrichment
- 2026-09-22 16:01 UTCEPSS rescore
- 2026-09-22 14:08 UTCEG score recompute
- 2026-09-22 14:08 UTCGHSA enrichment
- 2026-09-21 21:09 UTCEPSS rescore
- 2026-09-21 13:42 UTCEG score recompute
- 2026-09-21 13:42 UTCGHSA enrichment
- 2026-09-20 20:16 UTCEPSS rescore
- 2026-09-20 14:51 UTCEG score recompute
- 2026-09-20 14:51 UTCGHSA enrichment
- 2026-09-19 14:26 UTCEG score recompute
- 2026-09-19 14:26 UTCGHSA enrichment
- 2026-09-19 14:00 UTCEG score recompute
- 2026-09-19 14:00 UTCGHSA enrichment
- 2026-09-19 09:26 UTCEG score recompute
- 2026-09-19 08:31 UTCEG score recompute
- 2026-09-19 08:30 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-76579?
CVE-2026-76579 is a medium vulnerability published on September 19, 2026. 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…
When was CVE-2026-76579 disclosed?
CVE-2026-76579 was first published in the National Vulnerability Database on September 19, 2026, with the most recent update on September 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-76579 actively exploited?
CVE-2026-76579 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 71.1% of all scored CVEs.
What is the CVSS score of CVE-2026-76579?
CVE-2026-76579 has a CVSS v3 base score of 4.7 (NVD).
How do I remediate CVE-2026-76579?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-76579, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-76579
Is Your Infrastructure Affected by CVE-2026-76579?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.