Bug 1948982 (CVE-2021-21404) - CVE-2021-21404 syncthing: sending a relay message with a negative length field may lead to crash
Summary: CVE-2021-21404 syncthing: sending a relay message with a negative length fiel...
Keywords:
Status: CLOSED UPSTREAM
Alias: CVE-2021-21404
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1948983 1948984
Blocks:
TreeView+ depends on / blocked
 
Reported: 2021-04-13 08:12 UTC by Marian Rehak
Modified: 2021-04-13 12:39 UTC (History)
3 users (show)

Fixed In Version:
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Last Closed: 2021-04-13 12:39:21 UTC
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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.
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