CVE-2021-21392
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 1.28.0 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.
How to fix
- matrix synapse1.28.0 or later
- matrix-synapse1.28.0rc1, 1.28.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| matrix synapse | v < 1.28.0 | 1.28.0 |
| fedoraproject fedora | 34 | — |
| matrix-synapsePyPI | v < 1.28.0rc1, v < 1.28.0 | 1.28.0rc1, 1.28.0 |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.