Bug 2209956 (CVE-2022-39374)

Summary:	CVE-2022-39374 matrix-synapse: Synapse Denial of service due to incorrect application of event authorization rules during state resolution
Product:	[Other] Security Response	Reporter:	Avinash Hanwate <ahanwate>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED UPSTREAM	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	Keywords:	Security
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	matrix-synapse 1.68.0	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-05-25 15:11:58 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:	2209957
Bug Blocks:

Description Avinash Hanwate 2023-05-25 10:27:54 UTC

If Synapse and a malicious homeserver are both joined to the same room, the malicious homeserver can trick Synapse into accepting previously rejected events into its view of the current state of that room. This can be exploited in a way that causes all further messages and state changes sent in that room from the vulnerable homeserver to be rejected.

Synapse homeservers are affected by this issue if and only if they are joined to rooms which members of untrusted homeservers are joined or invited to.

- Synapse homeservers in rooms available over public federation are affected.
- Synapse homeservers with federation disabled are not affected.
- Synapse homeservers in a closed federation containing only trusted servers are not affected.
- Synapse homeservers which are only joined to rooms with federation disabled1 are not affected.

Comment 1 Avinash Hanwate 2023-05-25 10:28:13 UTC

Created matrix-synapse tracking bugs for this issue:

Affects: fedora-all [bug 2209957]

Comment 2 Product Security DevOps Team 2023-05-25 15:11:56 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.