CVE-2026-31951
MEDIUM
NVD
CVSS Score
6.8
Severity
MEDIUM
Published
Mar 27, 2026
Vendor
unknown
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.