Bug 1944138 (CVE-2021-21333)

Summary:	CVE-2021-21333 matrix-synapse: HTML injection in email and account expiry notifications
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, fedora
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	matrix-synapse 1.27.0	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-03-29 17:35:12 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:	1944139
Bug Blocks:

Description Michael Kaplan 2021-03-29 11:40:58 UTC

In Synapse before version 1.27.0, the notification emails sent for notifications for missed messages or for an expiring account are subject to HTML injection. In the case of the notification for missed messages, this could allow an attacker to insert forged content into the email. The account expiry feature is not enabled by default and the HTML injection is not controllable by an attacker. This is fixed in version 1.27.0.

Comment 1 Michael Kaplan 2021-03-29 11:41:02 UTC

External References:

https://github.com/matrix-org/synapse/commit/e54746bdf7d5c831eabe4dcea76a7626f1de73df
https://github.com/matrix-org/synapse/pull/9200
https://github.com/matrix-org/synapse/releases/tag/v1.27.0
https://github.com/matrix-org/synapse/security/advisories/GHSA-c5f8-35qr-q4fm

Comment 2 Michael Kaplan 2021-03-29 11:41:24 UTC

Created matrix-synapse tracking bugs for this issue:

Affects: fedora-all [bug 1944139]

Comment 3 Product Security DevOps Team 2021-03-29 17:35:12 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.