CVEvulnerability

CVE-2021-21333

6.1 MEDIUM Published 2021-03-26 Modified 2026-06-17 Official page ↗
Status
Modified
Published
2021-03-26
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
6.1 MEDIUM — CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N
CVSS 3.1 ([email protected])
6.1 MEDIUM — CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N
CVSS 2.0 ([email protected])
2.6 LOW — AV:N/AC:H/Au:N/C:N/I:P/A:N
Weaknesses
CWE-74, CWE-79

Description

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 configurations

• matrix synapse (< 1.27.0) • fedoraproject fedora 34

Related

Weakness · CWE (2)

  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation weakness

References