CVE-2025-66450

XSS in Librechat ≤ 0.8.1

Public PoCXSS

Published

11 December 2025

Modified

15 December 2025

Patch / advisory

View advisory

CVSS Score v4 8.6

Click a component to see what it means

Raw vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Score 0.0021 11th percentile

Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2025-66450 is a high-severity Basic XSS (CWE-80) vulnerability in Librechat Librechat. Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Content Injection (T1659); ranked at the 11th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

This vulnerability is AI-related — categorised as LLM Application Platforms; in the Privacy and Disclosure risk domain.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2025-202930

Vulnerability Data

LibreChat is a ChatGPT clone with additional features. In versions 0.8.0 and below, when a user posts a question, the iconURL parameter of the POST request can be modified by an attacker. The malicious code is then stored in the…

chat which can then be shared to other users. When sharing chats with a potentially malicious “tracker”, resources loaded can lead to loss of privacy for users who view the chat link that is sent to them. This issue is fixed in version 0.8.1.

CWE(s): CWE-80

AI Security AnalysisAI

AI Category: LLM Application Platforms
Risk Domain: Privacy and Disclosure
OWASP Top 10 for LLMs 2025: None mapped
Classification Reason: Matched keywords: chatgpt, librechat

Related Threats

MITRE ATT&CK Enterprise Techniques

T1659 Content Injection Initial Access

Adversaries may gain access and continuously communicate with victims by injecting malicious content into systems through online network traffic.

attack.mitre.org →

T1539 Steal Web Session Cookie Credential Access

An adversary may steal web application or service session cookies and use them to gain access to web applications or Internet services as an authenticated user without needing credentials.

attack.mitre.org →

T1189 Drive-by Compromise Initial Access

Adversaries may gain access to a system through a user visiting a website over the normal course of browsing.

attack.mitre.org →

Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-54025Same product: Librechat Librechat

CVE-2025-66452Same product: Librechat Librechat

CVE-2025-8848Same product: Librechat Librechat

CVE-2024-11169Same product: Librechat Librechat

CVE-2026-32625Same product: Librechat Librechat

CVE-2026-31951Same product: Librechat Librechat

CVE-2026-33265Same product: Librechat Librechat

CVE-2024-10361Same product: Librechat Librechat

CVE-2025-69222Same product: Librechat Librechat

CVE-2025-54868Same product: Librechat Librechat

Affected Assets

librechat

≤ 0.8.1

Mitigating Controls

Control response

Prevent

Stop it (NIST 800-53)

—

Detect

Catch it (NIST detect / respond)

—

Harden

Shrink the surface (DISA STIG)

—

Validate

Prove the fix (OWASP ASVS)

V1.2.1
V1.3.1
V1.3.3
V1.3.4

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover missing or incorrect neutralization of script tags through targeted XSS test cases.

SI-10 Information Input Validation good match

Input validation explicitly requires checking and neutralizing untrusted web inputs containing script-related characters before they reach a downstream renderer.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles include mandatory output encoding and neutralization of HTML metacharacters to stop injection at the source.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match

prevents

Secure SDLC practices directly require output encoding and input validation that prevent basic XSS.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match

finds

Security testing in development catches unneutralized script tags before release.

A.8.25 Secure development life cycle partial match

prevents

Secure SDLC mandates input validation and output encoding that directly prevent basic XSS.

A.8.26 Application security requirements partial match

prevents

Application security requirements explicitly call for neutralization of script-related HTML tags.

A.8.28 Secure coding partial match

prevents

Secure coding standards require proper escaping of <, >, & to block XSS.