Is CVE-2026-76579 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-76579 being exploited in the wild.

How severe is CVE-2026-76579?

Medium severity, with a CVSS score of 4.7, published 19 September 2026.

Which products and versions are affected?

LiteSpeed Cache up to and including 7.9.

Is there a fix for CVE-2026-76579?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-76579 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-76579?

Check whether you run LiteSpeed Cache at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-76579: LiteSpeed Cache reflected XSS via esi parameter

CVE-2026-76579 · Severity: medium · CVSS 4.7 · Published 2026-09-19

The LiteSpeed Cache plugin for WordPress contains a reflected cross-site scripting vulnerability that allows attackers to inject malicious scripts into web pages. An attacker must trick users into clicking a specially crafted link to execute the injected script in their browser, potentially stealing session data or performing unauthorized actions on their WordPress site.

Technologies: LiteSpeed Cache. Vendors: LiteSpeed.

Quick answers

Is CVE-2026-76579 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-76579 being exploited in the wild.
How severe is CVE-2026-76579?: Medium severity, with a CVSS score of 4.7, published 19 September 2026.
Which products and versions are affected?: LiteSpeed Cache up to and including 7.9.
Is there a fix for CVE-2026-76579?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-76579 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-76579?: Check whether you run LiteSpeed Cache at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability exists in the ESI (Edge Side Includes) parameter handling due to insufficient input sanitization and output escaping. An attacker can supply a validly signed GET 'esi' parameter along with an attacker-controlled POST 'esi' payload; PHP's default $_REQUEST merge order causes the POST value to take precedence, bypassing signature validation and allowing arbitrary script injection on unauthenticated page loads.

Affected products

LiteSpeed Cache up to and including 7.9

Timeline

2026-09-19: disclosed

References

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