CVE-2021-21333CWE-74

HTML injection in email and account expiry notifications

Medium · published March 26, 2021

CVSS v3.1
6.1
EPSS
1%
Percentile
71.4
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
6.1 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.01354 · 71.4th percentile
Weakness
CWE-74 · Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Published
2021-03-26T20:00Z
EPSS history
Timeline
  • 26 MAR 20:00Z
    HTML injection in email and account expiry notifications
    cvelistv5