CVE-2026-31951

published 2026-03-27

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 (Model Context Protocol) servers can include…

Priority P4 33 medium 5.7 CVSS 3.1

AV N AC L PR L UI R S U C H I N A N

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

3 ranges

Vendor	Product	Version range	Fixed in
danny-avila	librechat	—	—
librechat	librechat	—	—
librechat	librechat	>= 0.8.2 < 0.8.3	0.8.3

Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.

CWE-200