What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 8.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-27 · updated 2026-10-26
• Weakness: CWE-918

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.

Affected products

• danny-avila LibreChat: before 0.8.3; 0.8.3-rc1, 0.8.3-rc2 — fixed in 0.8.3

How to fix

Upgrade to a fixed version: danny-avila LibreChat 0.8.3. Check the vendor advisory for mitigations.

References

• https://github.com/danny-avila/LibreChat/security/advisories/GHSA-w5r7-4f94-vp4c
• https://github.com/danny-avila/LibreChat/security/advisories/GHSA-w5r7-4f94-vp4c

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