CVE-2026-31944
Published: 13 March 2026
Summary
CVE-2026-31944 is a high-severity Missing Authentication for Critical Function (CWE-306) vulnerability in Librechat Librechat. Its CVSS base score is 7.6 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 10.3th 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 APIs and Models; in the Protocol-Specific Risks risk domain.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Requires established identification and authentication to unlock, mitigating missing authentication for continued system access.
Requiring identification and rationale for actions allowed without authentication ensures critical functions are not left unprotected by forcing review of authentication requirements.
Authorizing mobile device connections to organizational systems ensures authentication is performed for this critical access function.
Guarantees critical functions are protected by mandatory invocation of the access control mechanism.
Auditing sessions makes it possible to detect access to critical functions without required authentication.
The assessment process confirms authentication is present and effective for critical functions, preventing exploitation from missing authentication.
Certification assesses that critical functions have required authentication controls in place.
Disabling non-essential functions and services eliminates the need to secure them, reducing exposure from missing authentication on unnecessary components.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Missing auth on OAuth callback enables remote exploitation of public-facing app (T1190) to misdirect and steal application access tokens (T1528) for use as alternate auth material on linked services (T1550.001).
NVD 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…
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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.
Deeper analysisAI
CVE-2026-31944 is a missing authentication vulnerability in the MCP (Model Context Protocol) OAuth callback endpoint of LibreChat, an open-source ChatGPT clone with additional features. Versions from 0.8.2 to 0.8.2-rc3 are affected, as the endpoint accepts redirects from identity providers and stores OAuth tokens for the user who initiated the flow without verifying that the browser is logged in or that the logged-in user matches the initiator. This flaw, classified under CWE-306 (Missing Authentication for Critical Function), carries a CVSS v3.1 base score of 7.6 (AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N).
A low-privileged LibreChat account holder can exploit the vulnerability by sending a malicious authorization URL to a victim user. When the victim completes the OAuth flow via their browser, the resulting tokens are stored on the attacker's LibreChat account rather than the victim's, granting the attacker access to the victim's MCP-linked services, such as Atlassian or Outlook, and enabling account takeover.
Published on 2026-03-13, the issue was addressed in LibreChat version 0.8.3-rc1. The official GitHub security advisory at https://github.com/danny-avila/LibreChat/security/advisories/GHSA-vf7j-7mrx-hp7g provides details on the patch and recommends upgrading to the fixed release for mitigation.
Details
- CWE(s)
Affected Products
AI Security AnalysisAI
- AI Category
- APIs and Models
- Risk Domain
- Protocol-Specific Risks
- OWASP Top 10 for LLMs 2025
- None mapped
- Classification Reason
- Matched keywords: mcp, model context protocol, mcp