CVE-2026-3375CWE-79

LiteSpeed Cache <= 7.7 - Unauthenticated Stored Cross-Site Scripting via QUIC.cloud CCSS/UCSS REST API Endpoints

High · published May 27, 2026

CVSS v3.1
7.2
EPSS
0%
Percentile
37.1
In the wild
Unconfirmed
What it is

The LiteSpeed Cache plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the /wp-json/litespeed/v1/notify_ccss and /wp-json/litespeed/v1/notify_ucss REST API endpoints in all versions up to, and including, 7.7. These endpoints accept CSS content from QUIC.cloud callback notifications and store it to disk without sanitization. The stored content is later rendered inline frontend page loads without output escaping. The access control protecting these endpoints is IP-based validation that can potentially be bypassed when the WordPress site is deployed behind a reverse proxy, load balancer, or CDN with certain configurations. This makes it possible for unauthenticated attackers, under certain conditions, to inject arbitrary JavaScript into CCSS/UCSS content.

The record
Technical detail
CVSS v3.1
7.2 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00438 · 37.1th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-05-27T07:45Z
EPSS history
Timeline
  • 27 MAY 07:45Z
    LiteSpeed Cache <= 7.7 - Unauthenticated Stored Cross-Site Scripting via QUIC.cloud CCSS/UCSS REST API Endpoints
    cvelistv5