CVE-2021-21333
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.
Does this matter?
Lower severity and a low EPSS score (1.39%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 6.1 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N
- EPSS
- 1.39% probability · 71th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-74, CWE-79
- Affected
- matrix/synapse · fedoraproject/fedora
- Source
- security-advisories@github.com
References
- https://github.com/matrix-org/synapse/commit/e54746bdf7d5c831eabe4dcea76a7626f1de73dfPatch, Third Party Advisory
- https://github.com/matrix-org/synapse/pull/9200Patch, Third Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v1.27.0Third Party Advisory
- https://github.com/matrix-org/synapse/security/advisories/GHSA-c5f8-35qr-q4fmPatch, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/
- https://github.com/matrix-org/synapse/commit/e54746bdf7d5c831eabe4dcea76a7626f1de73dfPatch, Third Party Advisory
- https://github.com/matrix-org/synapse/pull/9200Patch, Third Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v1.27.0Third Party Advisory
- https://github.com/matrix-org/synapse/security/advisories/GHSA-c5f8-35qr-q4fmPatch, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.