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Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLXg0NjItODlwZi02cjVo
Crash due to malformed relay protocol message
Impact
-
syncthing
can be caused to crash and exit if sent a malformed relay protocol message message with a negative length field. -
The relay server
strelaysrv
can be caused to crash and exit if sent a malformed relay protocol message with a negative length field.
At no point is sensitive data exposed or liable to be altered due to this issue. Sensitive data is never exposed to relay operators. Syncthing itself would need to be lured to connect to a malicious relay server in order to exploit the issue.
Patches
Fixed in version 1.15.0.
Workarounds
-
No known workaround for
strelaysrv
. -
syncthing
can be configured to not use relays, or to only use specific, trusted relays. If Syncthing is used in a closed environment or with relaying disabled, i.e., it does not communicate with unknown relays, Syncthing is not vulnerable.
For more information
If you have any questions or comments about this advisory, please discuss it on the forum.
Thanks to Wojciech Paciorek for discovering and reporting this issue.
Permalink: https://github.com/advisories/GHSA-x462-89pf-6r5hJSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLXg0NjItODlwZi02cjVo
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Low
Classification: General
Published: about 2 years ago
Updated: 4 months ago
CVSS Score: 7.5
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Identifiers: GHSA-x462-89pf-6r5h, CVE-2021-21404
References:
- https://github.com/syncthing/syncthing/security/advisories/GHSA-x462-89pf-6r5h
- https://nvd.nist.gov/vuln/detail/CVE-2021-21404
- https://github.com/syncthing/syncthing/commit/fb4fdaf4c0a79c22cad000c42ac1394e3ccb6a97
- https://github.com/syncthing/syncthing/releases/tag/v1.15.0
- https://pkg.go.dev/github.com/syncthing/syncthing
- https://github.com/advisories/GHSA-x462-89pf-6r5h
Affected Packages
go:github.com/syncthing/syncthing
Versions: < 1.15.0Fixed in: 1.15.0