Bug 1948982 (CVE-2021-21404)

Summary:	CVE-2021-21404 syncthing: sending a relay message with a negative length field may lead to crash
Product:	[Other] Security Response	Reporter:	Marian Rehak <mrehak>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED UPSTREAM	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	decathorpe, eclipseo, go-sig
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-04-13 12:39:21 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1948983, 1948984
Bug Blocks:

Description Marian Rehak 2021-04-13 08:12:49 UTC

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.

Reference:

https://github.com/syncthing/syncthing/security/advisories/GHSA-x462-89pf-6r5h

Fix:

https://github.com/syncthing/syncthing/commit/fb4fdaf4c0a79c22cad000c42ac1394e3ccb6a97

Comment 1 Marian Rehak 2021-04-13 08:13:26 UTC

Created syncthing tracking bugs for this issue:

Affects: epel-8 [bug 1948984]
Affects: fedora-all [bug 1948983]

Comment 2 Product Security DevOps Team 2021-04-13 12:39:21 UTC

This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.