CVE-2025-66452 LibreChat's lack of JSON parsing error handling can lead to XSS

Medium 5.3 Published 11 Dec 2025 Updated 12 Dec 2025

Attackers can inject malicious scripts via JSON parsing errors in LibreChat, potentially executing code in victim browsers.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2025-66452?

CVE-2025-66452 is a medium-severity cross-site scripting vulnerability in Librechat Librechat, published on 11 Dec 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

LibreChat is a ChatGPT clone with additional features. In versions 0.8.0 and below, there is no handler for JSON parsing errors; SyntaxError from express.json() includes user input in the error message, which gets reflected in responses. User input (including HTML/JavaScript) can be exposed in error responses, creating an XSS risk if Content-Type isn't strictly enforced. This issue does not have a fix at the time of publication.

Weakness: CWE-79

Which versions are affected by CVE-2025-66452?

It affects 1 product.

Products include Librechat Librechat.

How do I fix CVE-2025-66452?

No fix has been published for CVE-2025-66452 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-2025-66452 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-66452 exists.

All Librechat Librechat vulnerabilities

Sources

Also known as GHSA-q6c5-gvj5-c264.