CVE-2026-54030: LibreChat: Missing Resource Parameter Validation in MCP OAuth Flow

Severity: critical (CVSS 9.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-06-25 · updated 2026-10-25
Weakness: CWE-346

Description

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.

Affected products

danny-avila LibreChat: through 0.8.4; 0.8.5-rc1

References

https://github.com/danny-avila/LibreChat/security/advisories/GHSA-gvpj-vm2f-2m23
https://github.com/danny-avila/LibreChat/security/advisories/GHSA-gvpj-vm2f-2m23

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