CVE-2026-47684 Sync-in Server: SSRF protection bypass via IPv4-mapped IPv6 addresses in regExpPrivateIP
Attackers can bypass SSRF protections in Sync-in Server by using IPv4-mapped IPv6 addresses to access internal resources.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-47684?
CVE-2026-47684 is a high-severity server-side request forgery vulnerability in Sync-in server, published on 16 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-918
Which versions are affected by CVE-2026-47684?
2 open source packages ship an affected version, including @sync-in/server.
| Package | Affected | Fixed in |
|---|---|---|
@sync-in/server npm | All versions | 2.3.0 |
@sync-in/server npm | All versions | 2.3.0 |
How do I fix CVE-2026-47684?
Upgrade @sync-in/server to 2.3.0 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-47684 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-47684 exists.
Sources
Also known as GHSA-q4x5-8cj6-52wg.