CVEvulnerability

CVE-2026-31951

5.7 MEDIUM Published 2026-03-27 Modified 2026-10-26 Official page ↗
Status
Analyzed
Published
2026-03-27
Last modified
2026-10-26
Assigner
[email protected]
CVSS 3.1 ([email protected])
6.8 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N
CVSS 3.1 ([email protected])
5.7 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
Weaknesses
CWE-200

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.

Affected configurations

• librechat librechat (>= 0.8.2 < 0.8.3) • librechat librechat 0.8.3

Related

Weakness · CWE (1)

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

References