Upstream information

CVE-2021-21404 at MITRE

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.

SUSE information

Overall state of this security issue: Resolved

This issue is currently rated as having important severity.

CVSS v2 Scores
CVSS detail National Vulnerability Database
Base Score 5
Vector AV:N/AC:L/Au:N/C:N/I:N/A:P
Access Vector Network
Access Complexity Low
Authentication None
Confidentiality Impact None
Integrity Impact None
Availability Impact Partial
CVSS v3 Scores
CVSS detail National Vulnerability Database
Base Score 7.5
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Impact None
Integrity Impact None
Availability Impact High
CVSSv3 Version 3.1
SUSE Bugzilla entry: 1184428 [IN_PROGRESS]

SUSE Security Advisories:

List of released packages

Product(s) Fixed package version(s) References
SUSE Package Hub 15 SP2
  • syncthing >= 1.15.1-bp152.2.3.1
  • syncthing-relaysrv >= 1.15.1-bp152.2.3.1
 Patchnames:
openSUSE-2021-713
openSUSE Leap 15.2
  • syncthing >= 1.15.1-lp152.2.3.1
  • syncthing-relaysrv >= 1.15.1-lp152.2.3.1
 Patchnames:
openSUSE-2021-688
openSUSE Tumbleweed
  • syncthing >= 1.18.2-2.1
  • syncthing-relaysrv >= 1.18.2-2.1
 Patchnames:
openSUSE-Tumbleweed-2024-11417

SUSE Timeline for this CVE

CVE page created: Wed Apr 7 04:24:35 2021
CVE page last modified: Sat Nov 1 22:23:10 2025