https://cve.radiocsirt.org/rss/recent/all/10 Most recent entries from all 2026-10-24T23:20:37.049191+00:00 Vulnerability-Lookup csirt@opendfir.org python-feedgen Contains only the most 10 recent entries. https://cve.radiocsirt.org/vuln/euvd-2026-22131 EUVD-2026-22131 2026-10-24T23:20:37.076426+00:00 EUVD-2026-22131 https://cve.radiocsirt.org/vuln/fkie_cve-2021-21333 fkie_cve-2021-21333 2026-10-24T23:20:37.076471+00:00

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.

 https://cve.radiocsirt.org/vuln/ghsa-c5f8-35qr-q4fm GHSA-c5f8-35qr-q4fm — HTML injection in email and account expiry notifications 2026-10-24T23:20:37.076508+00:00

Affected: PyPI: matrix-synapse

### Impact 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.

### Patches This issue is fixed in #9200.

### Workarounds For the missed messages notifications:

The `notif.html`, `notif_mail.html`, and `room.html` templates can be overridden with custom templates that manually escapes the variables using [JInja2's `escape` filter](https://jinja.palletsprojects.com/en/2.11.x/templates/#escape). See the `email.template_dir` setting.

For the account expiry notifications:

1. Account expiry can be disabled via the `account_validity.enabled` setting.

2. The `notice_expiry.html` template can be overridden with a custom template that manually escapes the variables using [JInja2's `escape` filter](https://jinja.palletsprojects.com/en/2.11.x/templates/#escape). See the `email.template_dir` setting.

 https://cve.radiocsirt.org/vuln/gsd-2021-21333 gsd-2021-21333 2026-10-24T23:20:37.076548+00:00 gsd-2021-21333 https://cve.radiocsirt.org/vuln/pysec-2021-134 PYSEC-2021-134 2026-10-24T23:20:37.076561+00:00

Affected: PyPI: matrix-synapse

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.

 https://cve.radiocsirt.org/vuln/ubuntu-cve-2021-21333 UBUNTU-CVE-2021-21333 2026-10-24T23:20:37.076583+00:00

Affected: Ubuntu:Pro:18.04:LTS: matrix-synapse, Ubuntu:Pro:20.04:LTS: matrix-synapse

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.