First published: Mon Apr 12 2021(Updated: )
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 1.28.0 requests to user provided domains were not restricted to external IP addresses when transitional IPv6 addresses were used. Outbound requests to federation, identity servers, when calculating the key validity for third-party invite events, sending push notifications, and generating URL previews are affected. This could cause Synapse to make requests to internal infrastructure on dual-stack networks. See referenced GitHub security advisory for details and workarounds.
Credit: security-advisories@github.com
Affected Software | Affected Version | How to fix |
---|---|---|
Matrix Synapse | <1.28.0 | |
Fedoraproject Fedora | =34 |
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CVE-2021-21392 is a vulnerability in Synapse, a Matrix reference homeserver, that allows requests to user provided domains without restrictions on IP addresses.
CVE-2021-21392 affects Matrix Synapse versions up to and excluding 1.28.0.
CVE-2021-21392 has a severity rating of 6.3 (medium).
To fix CVE-2021-21392, update to version 1.28.0 or newer of Matrix Synapse.
Yes, here are some references for CVE-2021-21392: [GitHub Pull Request](https://github.com/matrix-org/synapse/pull/9240), [GitHub Security Advisory](https://github.com/matrix-org/synapse/security/advisories/GHSA-5wrh-4jwv-5w78), [Fedora Project Announcement](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/).