CVE-2026-54030CWE-346

LibreChat: Missing Resource Parameter Validation in MCP OAuth Flow

High · published June 25, 2026

CVSS v3.1
8.0
EPSS
0%
Percentile
5.7
In the wild
Unconfirmed
What it is

LibreChat is an enhanced ChatGPT clone that supports multiple AI providers. Prior to 0.8.5, LibreChat's MCP OAuth implementation does not validate that the resource parameter from OAuth Protected Resource metadata (RFC 9728) matches the configured MCP server URL, allowing a malicious MCP server to steal access tokens intended for a legitimate server. This vulnerability is fixed in 0.8.5.

The record
Technical detail
CVSS v3.1
8.0 · HIGH
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00168 · 5.7th percentile
Weakness
CWE-346 · Origin Validation Error
Published
2026-06-25T15:48Z
EPSS history
Timeline
  • 25 JUN 15:48Z
    LibreChat: Missing Resource Parameter Validation in MCP OAuth Flow
    cvelistv5