CVE-2026-31951 (GCVE-0-2026-31951)
Vulnerability from cvelistv5 – Published: 2026-03-27 19:29 – Updated: 2026-03-31 13:46
VLAI
EPSS
VEX
Title
LibreChat's MCP Server Header Injection Enables OAuth Token Theft
Summary
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.
Severity
6.8 (Medium)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-31 13:45 UTC
CWE
- CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/danny-avila/LibreChat/security… | x_refsource_CONFIRM |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| danny-avila | LibreChat |
Affected:
>= v0.8.2-rc1, <= v0.8.3-rc1
|
guessed |
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