CVE-2026-31951: LibreChat is a ChatGPT clone with additional features. In versions 0.8.2-rc1 through 0.8.3-rc1, user-created MCP…
CVE-2026-31951 · Severity: medium · CVSS 6.8 · Published 2026-03-27
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.
No. Junglewise Threat Intelligence has no report of CVE-2026-31951 being exploited in the wild.
How severe is CVE-2026-31951?
Medium severity, with a CVSS score of 6.8, published 27 March 2026.
Which products and versions are affected?
LibreChat. The advisory does not name versions.
Is there a fix for CVE-2026-31951?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
Am I affected by CVE-2026-31951?
Check whether you run LibreChat. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.