CVE-2026-31951— LibreChat's MCP Server Header Injection Enables OAuth Token Theft
Get alerts for future matching vulnerabilitiesLog in to subscribe
I. Basic Information for CVE-2026-31951
Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗ Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.
Vulnerability Title
LibreChat's MCP Server Header Injection Enables OAuth Token Theft
Source: NVD (National Vulnerability Database)
Vulnerability Description
LibreChat is a ChatGPT clone with additional features. In versions 0.8.2-rc1 through 0.8.3-rc1, user-created MCP (Model Context Protocol) servers can include arbitrary HTTP headers that undergo credential placeholder substitution. An attacker can create a malicious MCP server with headers containing `{{LIBRECHAT_OPENID_ACCESS_TOKEN}}` (and others), causing victims who call tools on that server to have their OAuth tokens exfiltrated. Version 0.8.3-rc2 fixes the issue.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
信息暴露
Source: NVD (National Vulnerability Database)
Vulnerability Title
LibreChat 信息泄露漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
LibreChat是LibreChat开源的一个免费、高度可定制的统一 AI 对话平台，能够在一个界面中聚合并运行来自任意厂商的大模型。 LibreChat 0.8.2-rc1至0.8.3-rc1版本存在信息泄露漏洞，该漏洞源于用户创建的MCP服务器可包含经过凭据占位符替换的任意HTTP标头，可能导致攻击者创建包含特定令牌的恶意MCP服务器，致使调用该服务器上工具的受害者OAuth令牌被窃取。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| danny-avila | LibreChat | >= v0.8.2-rc1, <= v0.8.3-rc1 | - |
II. Public POCs for CVE-2026-31951
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POCPremium
No public POC found.
Login to generate AI POCIII. Intelligence Information for CVE-2026-31951
请登录查看更多情报信息。
Same Patch Batch · danny-avila · 2026-03-27 · 4 CVEs total
| CVE-2026-31943 | 8.5 HIGH | LibreChat has SSRF protection bypass via IPv4-mapped IPv6 normalization in isPrivateIP |
| CVE-2026-31945 | 7.7 HIGH | LibreChat Server-Side Request Forgery using DNS resolution |
| CVE-2026-31950 | 5.3 MEDIUM | LibreChat's IDOR in SSE Stream Subscription Allows Reading Other Users' Chats |
IV. Related Vulnerabilities
Same product: LibreChat
- CVE-2026-34371
LibreChat Affected by Arbitrary File Write via `execute_code - CVE-2026-31950
LibreChat's IDOR in SSE Stream Subscription Allows Reading O - CVE-2026-31945
LibreChat Server-Side Request Forgery using DNS resolution - CVE-2026-31943
LibreChat has SSRF protection bypass via IPv4-mapped IPv6 no - CVE-2026-33265
LibreChat 安全漏洞
Same vendor: danny-avila
- CVE-2026-34371
LibreChat Affected by Arbitrary File Write via `execute_code - CVE-2026-31950
LibreChat's IDOR in SSE Stream Subscription Allows Reading O - CVE-2026-31945
LibreChat Server-Side Request Forgery using DNS resolution - CVE-2026-31943
LibreChat has SSRF protection bypass via IPv4-mapped IPv6 no - CVE-2025-41258
LibreChat RAG API Authentication Bypass
Same weakness: CWE-200
- CVE-2026-42333
quarkus-openapi-generator has overly broad path-parameter ma - CVE-2026-8198
Activity Logs, User Activity Tracking, Multisite Activity Lo - CVE-2026-42456
AnythingLLM: Cross-User TTS Audio Disclosure via Chat ID (ID - CVE-2026-41520
Cillium exposes sensitive information included in the cilium - CVE-2026-25199
Apache CloudStack: Proxmox Extension Allows Unauthorized Cro
V. Comments for CVE-2026-31951
No comments yet