Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Syncthing | Syncthing | < 1.15.0 |
Related Weaknesses (CWE)
References
- https://github.com/syncthing/syncthing/commit/fb4fdaf4c0a79c22cad000c42ac1394e3cPatchThird Party Advisory
- https://github.com/syncthing/syncthing/releases/tag/v1.15.0Release NotesThird Party Advisory
- https://github.com/syncthing/syncthing/security/advisories/GHSA-x462-89pf-6r5hThird Party Advisory
- https://pkg.go.dev/github.com/syncthing/syncthingProductThird Party Advisory
- https://github.com/syncthing/syncthing/commit/fb4fdaf4c0a79c22cad000c42ac1394e3cPatchThird Party Advisory
- https://github.com/syncthing/syncthing/releases/tag/v1.15.0Release NotesThird Party Advisory
- https://github.com/syncthing/syncthing/security/advisories/GHSA-x462-89pf-6r5hThird Party Advisory
- https://pkg.go.dev/github.com/syncthing/syncthingProductThird Party Advisory
FAQ
What is CVE-2021-21404?
CVE-2021-21404 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 len...
How severe is CVE-2021-21404?
CVE-2021-21404 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-21404?
Check the references section above for vendor advisories and patch information. Affected products include: Syncthing Syncthing.