CVE-2026-3375 LiteSpeed Cache <= 7.7 - Unauthenticated Stored Cross-Site Scripting via QUIC.cloud CCSS/UCSS REST API Endpoints
Unauthenticated attackers can inject arbitrary JavaScript via REST API endpoints in the LiteSpeed Cache WordPress plugin, potentially leading to code execution or account takeover.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-3375?
CVE-2026-3375 is a high-severity cross-site scripting vulnerability in litespeedtech LiteSpeed Cache, published on 27 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-79
Which versions are affected by CVE-2026-3375?
How do I fix CVE-2026-3375?
No fix has been published for CVE-2026-3375 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-3375 being exploited?
There is no known exploitation of CVE-2026-3375 in the wild and no public exploit code.
Sources
Also known as GHSA-hf4x-3pgg-4r9c.