CVEvulnerability

CVE-2021-21404

7.5 HIGH Published 2021-04-06 Modified 2026-06-17 Official page ↗
Status
Modified
Published
2021-04-06
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1 ([email protected])
7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0 ([email protected])
5.0 MEDIUM — AV:N/AC:L/Au:N/C:N/I:N/A:P
Weaknesses
CWE-20

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.

Affected configurations

• syncthing syncthing (< 1.15.0)

Related

Weakness · CWE (1)

  • CWE-20 Improper Input Validation weakness

References