CVE-2026-31951
MEDIUM
MEDIUM
Priority: 0.01
BB Relevance:
51/100
Published: 2026-03-27
Modified: 2026-10-26
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
Conf. Impact
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
Low
UI:
Required
S:
Unchanged
C:
High
I:
None
A:
None
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.
Weakness Classification (1)
Affected Software (2)
References & Advisories (1)
Exploit
Vendor Advisory