# 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…

Source: https://junglewise.ai/threats/cve-2026-31951-librechat-is-a-chatgpt-clone-with-additional-features-in-versions  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-27  
License: CC BY 4.0 with a link back

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.

Technologies: [LibreChat](https://junglewise.ai/threats/technologies/librechat). Vendors: [LibreChat](https://junglewise.ai/threats/vendors/librechat).

## Quick answers

**Is CVE-2026-31951 exploited in the wild?** 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.

## Affected products

- LibreChat

## Related threats

- [LibreChat 2FA bypass via unauthenticated backup code regeneration](https://junglewise.ai/threats/cve-2026-54040-librechat-2fa-bypass-via-unauthenticated-backup-code-regeneration)
- [LibreChat resource exhaustion via missing rate limiting in duplicate endpoint](https://junglewise.ai/threats/cve-2026-54037-librechat-resource-exhaustion-via-missing-rate-limiting-in)
- [LibreChat SSRF via custom endpoint baseURL](https://junglewise.ai/threats/cve-2026-54033-librechat-ssrf-via-custom-endpoint-baseurl)
- [LibreChat token theft via missing OAuth resource validation in MCP](https://junglewise.ai/threats/cve-2026-54030-librechat-token-theft-via-missing-oauth-resource-validation-in)
- [danny-avila LibreChat IDOR in message deletion endpoint](https://junglewise.ai/threats/cve-2026-54029-danny-avila-librechat-idor-in-message-deletion-endpoint)