Bug 1906325 (CVE-2020-26257)

Summary:	CVE-2020-26257 matrix-synapse: incorrect parameters could result in DoS
Product:	[Other] Security Response	Reporter:	Michael Kaplan <mkaplan>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED UPSTREAM	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	djc
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	matrix-synapse 1.23.1	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-12-10 12:47:00 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:	1906326
Bug Blocks:

Description Michael Kaplan 2020-12-10 09:33:45 UTC

Matrix is an ecosystem for open federated Instant Messaging and VoIP. Synapse is a reference "homeserver" implementation of Matrix. A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the path of a `/send_join`, `/send_leave`, `/invite` or `/exchange_third_party_invite` request. This can lead to a denial of service in which future events will not be correctly sent to other servers over federation. This affects any server which accepts federation requests from untrusted servers. The Matrix Synapse reference implementation before version 1.23.1 the implementation is vulnerable to this injection attack. Issue is fixed in version 1.23.1. As a workaround homeserver administrators could limit access to the federation API to trusted servers (for example via `federation_domain_whitelist`).

External References:

https://github.com/matrix-org/synapse/blob/develop/CHANGES.md#synapse-1231-2020-12-09
https://github.com/matrix-org/synapse/commit/3ce2f303f15f6ac3dc352298972dc6e04d9b7a8b
https://github.com/matrix-org/synapse/pull/8776
https://github.com/matrix-org/synapse/security/advisories/GHSA-hxmp-pqch-c8mm

Comment 1 Michael Kaplan 2020-12-10 09:34:06 UTC

Created matrix-synapse tracking bugs for this issue:

Affects: fedora-all [bug 1906326]

Comment 2 Product Security DevOps Team 2020-12-10 12:47:00 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.