CVE-2021-21404
Description
Syncthing is a continuous file synchronization program. In Syncthing before version 1.15.0, the relay server `strelaysrv` can be caused to crash and exit by sending a relay message with a negative length field. Similarly, Syncthing itself can crash for the same reason if given a malformed message from a malicious relay server when attempting to join the relay. Relay joins are essentially random (from a subset of low latency relays) and Syncthing will by default restart when crashing, at which point it's likely to pick another non-malicious relay. This flaw is fixed in version 1.15.0.
How to fix
- syncthing syncthing1.15.0 or later
- github.com/syncthing/syncthing1.15.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| syncthing syncthing | v < 1.15.0 | 1.15.0 |
| github.com/syncthing/syncthingGo | v < 1.15.0 | 1.15.0 |
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