CVE-2026-31943 LibreChat has SSRF protection bypass via IPv4-mapped IPv6 normalization in isPrivateIP

High 8.5 Published 27 Mar 2026 Updated 31 Mar 2026

Authenticated users can bypass SSRF protections to access internal network resources and cloud metadata services.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-31943?

CVE-2026-31943 is a high-severity server-side request forgery vulnerability in Librechat Librechat, published on 27 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

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.

Weakness: CWE-918

Which versions are affected by CVE-2026-31943?

It affects 1 product.

Products include Librechat Librechat.

How do I fix CVE-2026-31943?

No fix has been published for CVE-2026-31943 yet. Limit exposure of the affected software until one is available.

Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.

Is CVE-2026-31943 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-31943 exists.

All Librechat Librechat vulnerabilities

Sources

Also known as GHSA-w5r7-4f94-vp4c.