CVE-2026-31944
LibreChat MCP OAuth callback does not validate browser session — allows token theft via redirect link
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.
CVSS Vector Breakdown
AV:NAttack VectorAC:LAttack ComplexityPR:LPrivileges RequiredUI:RUser InteractionS:CScopeC:HConfidentialityI:LIntegrityA:NAvailabilityWeaknesses
Affected Products
Attack Graph
Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.
Exploitability
MITRE ATT&CK
2 techniquesReferences
Timeline
Unlock Complete Vulnerability Intelligence
Get the full picture for CVE-2026-31944 and every CVE in our database. Create a free account — no credit card required.
Create Free Account