CVE-2026-58270 Sync-in Server has a ReDoS via Unsanitized Regex in Sync Diff `pathFilters`
Attackers can cause a denial of service in Sync-in Server by submitting malicious regex patterns that block the event loop.
- 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-2026-58270?
CVE-2026-58270 is a medium-severity denial of service vulnerability in Sync-in server, published on 21 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Sync-in Server is an open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.4.0, the sync diff endpoint compiles a user-supplied string into a `RegExp` with no complexity validation. A catastrophic-backtracking pattern (e.g. `^(a+)+b`) blocks the Node.js event loop, making the entire server unresponsive to all users until the container is restarted. Version 2.4.0 patches the issue.
Weakness: CWE-1333
Which versions are affected by CVE-2026-58270?
2 open source packages ship an affected version, including @sync-in/server.
| Package | Affected | Fixed in |
|---|---|---|
@sync-in/server npm | All versions | 2.4.0 |
@sync-in/server npm | All versions | 2.4.0 |
How do I fix CVE-2026-58270?
Upgrade @sync-in/server to 2.4.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-58270 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58270 exists.
Sources
Also known as GHSA-jx63-h26r-8cph.