HTML injection in email and account expiry notifications
CVE-2021-21333

6.1MEDIUM

Key Information:

Vendor

Matrix-org

Status
Synapse
Vendor
CVE Published:
26 March 2021

What is CVE-2021-21333?

Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. 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.

Affected Version(s)

synapse < 1.27.0

References

https://github.com/matrix-org/synapse/releases/tag/v1.27.0
x_refsource_MISC
https://github.com/matrix-org/synapse/pull/9200
x_refsource_MISC
https://github.com/matrix-org/synapse/commit/e54746bdf7d5...
x_refsource_MISC

CVSS V3.1

Score:
6.1
Severity:
MEDIUM
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
Required
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.