CVE-2026-31951

MediumCVSS 5.7/10Last modified Jun 17, 2026

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.

Metrics

CVSS 3.1 5.7/10CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N

Weakness enumeration

CWE-200

Affected software

No affected versions have been published.

Timeline

Published: Mar 27, 2026
Last modified: Jun 17, 2026
NVD status: Analyzed

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