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Vulnerability record · CVE-2026-31944 · published 13 March 2026

CVE-2026-31944: Librechat missing authentication for critical function vulnerability

Librechat · Librechat

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.

7.6 CVSS 3.1 High EPSS 0.29% · top 80.4% CWE-306 · Missing authentication for critical function
7.6CVSS 3.1 base score
0.29%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
1References, 1 tagged exploit
17 Jun 2026Last modified by 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 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:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/danny-avila/LibreChat/security/advisories/GHSA-vf7j-7mrx-hp7g ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-31944), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.