CVE-2026-31943

Name: CVE-2026-31943
Creator: NVD / NIST
Published: 2026-03-27T20:16:29.897+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.5/10EPSS 0.21%

Last modified Jun 17, 2026

CVE-2026-31943 is a high-severity vulnerability rated 8.5/10 on the CVSS scale. 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. EPSS estimates a 0.21% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

8.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

EPSS Probability

0.21%

11.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-918

Affected Software

Vendor	Product	Versions	Update
Librechat	Librechat	< 0.8.3	—
Librechat	Librechat	0.8.3	Rc1

References

https://github.com/danny-avila/LibreChat/security/advisories/GHSA-w5r7-4f94-vp4cExploit, Vendor Advisory
https://github.com/danny-avila/LibreChat/security/advisories/GHSA-w5r7-4f94-vp4cExploit, Vendor Advisory

Timeline

Published: Mar 27, 2026
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2026-31943?

How severe is CVE-2026-31943?

CVE-2026-31943 has a CVSS score of 8.5/10 (HIGH severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.

How do I fix CVE-2026-31943?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-31943?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST