Main Vulnerability Database Vulnerabilities #VU79774

Input validation error in syncthing - CVE-2021-21404

Published: August 21, 2023

Vulnerability identifier: #VU79774

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2021-21404

CWE-ID: CWE-20

Exploitation vector: Remote access

Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input during synchronization. A remote attacker can send a relay message with a negative length field and crash the server.

Affected software

syncthing
Fedora
syncthing

How to mitigate CVE-2021-21404

Install updates from vendor's website.

syncthing - update to 1.15.0
syncthing - update to 1.18.6-3.el8

External References

https://github.com/syncthing/syncthing/releases/tag/v1.15.0
https://github.com/syncthing/syncthing/commit/fb4fdaf4c0a79c22cad000c42ac1394e3ccb6a97
https://github.com/syncthing/syncthing/security/advisories/GHSA-x462-89pf-6r5h

Related Security Bulletins