CVE-2026-31943: LibreChat has SSRF protection bypass via IPv4-mapped IPv6 normalization in isPrivateIP
LibreChat is a ChatGPT clone with additional features. Prior to version 0.8.3, isPrivateIP() in packages/api/src/auth/domain.ts fails to detect IPv4-mapped IPv6 addresses in their hex-normalized form, allowing any authenticated user to bypass SSRF protection and make the server issue HTTP requests to internal network resources — including cloud metadata services (e.g., AWS 169.254.169.254), loopback, and RFC1918 ranges. Version 0.8.3 fixes the issue.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-31943?
CVE-2026-31943 is classified as a medium severity vulnerability due to the potential for bypassing security controls.
How do I fix CVE-2026-31943?
To mitigate CVE-2026-31943, upgrade LibreChat to version 0.8.3 or later where the vulnerability is resolved.
What type of vulnerability is CVE-2026-31943?
CVE-2026-31943 is an SSRF (Server-Side Request Forgery) protection bypass vulnerability.
What is affected by CVE-2026-31943?
CVE-2026-31943 affects LibreChat versions prior to 0.8.3.
Can I still use LibreChat if CVE-2026-31943 is present?
It is highly recommended to update to the latest version of LibreChat to ensure protection against CVE-2026-31943.