Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-31944

Severity CVSS v4.0:
Pending analysis
Type:
CWE-306 Missing Authentication for Critical Function
Publication date:
13/03/2026
Last modified:
17/03/2026

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.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 7.60 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): Required
Scope (S): Changed
Confidentiality (C): High
Integrity (I): Low
Availability (A): None

Base Score 3.x
7.60
Severity 3.x
HIGH

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:librechat:librechat:0.8.2:-:*:*:*:*:*:*
cpe:2.3:a:librechat:librechat:0.8.2:rc1:*:*:*:*:*:*
cpe:2.3:a:librechat:librechat:0.8.2:rc2:*:*:*:*:*:*
cpe:2.3:a:librechat:librechat:0.8.2:rc3:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools