CVE-2026-31951

MEDIUM EPSS 15.4%
Published Mar 27, 20263mo ago · Modified Jun 17, 20261w ago
5.7 CVSS 3.1
Medium
Find Similar
Published Mar 27, 2026 3mo ago
Last Modified Jun 17, 2026 1w ago

Description

LibreChat is a ChatGPT clone with additional features. In versions 0.8.2-rc1 through 0.8.3-rc1, user-created MCP (Model Context Protocol) servers can include arbitrary HTTP headers that undergo credential placeholder substitution. An attacker can create a malicious MCP server with headers containing `{{LIBRECHAT_OPENID_ACCESS_TOKEN}}` (and others), causing victims who call tools on that server to have their OAuth tokens exfiltrated. Version 0.8.3-rc2 fixes the issue.

CVSS Details

Base Score
5.7
Exploitability
2.1
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required Low
User Interaction Required
Scope Unchanged
Confidentiality High
Integrity None
Availability None

Threat Intelligence

EPSS Exploit Probability
15.4% percentile
Exploit & Patch Status
Public Exploit Known
No Patch Available

Weaknesses 1

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor Information Exposure

Affected Products 2

VendorProductVersionRange
librechatlibrechat*≥0.8.2  –  <0.8.3
librechatlibrechat0.8.3any

References 1

  • github.com https://github.com/danny-avila/LibreChat/security/advisories/GHSA-pmw7-gqwj-f954
    ExploitVendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.