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CVE-2026-31944— LibreChat MCP OAuth callback does not validate browser session — allows token theft via redirect link

Quick assessment

Affected
danny-avila LibreChat
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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至0.8.2-rc3版本存在访问控制错误漏洞，该漏洞源于MCP OAuth回调端点未验证浏览器登录状态或用户匹配，可能导致账户接管。

CVSS 7.6 · High EPSS 0.30% · P22
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I. Basic Information for CVE-2026-31944

Vulnerability Information
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Vulnerability Title
LibreChat MCP OAuth callback does not validate browser session — allows token theft via redirect link
Source: CVE Program / CVE List V5
Vulnerability Description
LibreChat is a ChatGPT clone with additional features. From 0.8.2 to 0.8.2-rc3, The MCP (Model Context Protocol) OAuth callback endpoint accepts the redirect from the identity provider and stores OAuth tokens for the user who initiated the flow, without verifying that the browser hitting the redirect URL is logged in or that the logged-in user matches the initiator. An attacker can send the authorization URL to a victim; when the victim completes the flow, the victim’s OAuth tokens are stored on the attacker’s LibreChat account, enabling account takeover of the victim’s MCP-linked services (e.g. Atlassian, Outlook). This vulnerability is fixed in 0.8.3-rc1.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
关键功能的认证机制缺失
Source: CVE Program / CVE List V5
Vulnerability Title
LibreChat 访问控制错误漏洞
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至0.8.2-rc3版本存在访问控制错误漏洞，该漏洞源于MCP OAuth回调端点未验证浏览器登录状态或用户匹配，可能导致账户接管。
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, <= 0.8.2-rc3 -

II. Public POCs for CVE-2026-31944

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III. Intelligence Information for CVE-2026-31944

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Vendor Advisories for CVE-2026-31944 (1)

IV. Related Vulnerabilities

Same product: LibreChat
Same vendor: danny-avila
Same weakness: CWE-306

V. Comments for CVE-2026-31944

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