CVE-2021-21392 SUSE CVE security@suse.de SUSE Security Team SUSE CVE-2021-21392 Interim 1 6 2025-02-17T00:52:15Z current 2021-05-30T14:48:13Z 2025-02-17T00:52:15Z cve-database/bin/generate-cvrf-cve.pl 2020-12-27T01:00:00Z CVE-2021-21392 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. The CVRF data is provided by SUSE under the Creative Commons License 4.0 with Attribution (CC-BY-4.0). https://www.suse.com/support/security/rating/ SUSE Security Ratings 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. CVE-2021-21392 moderate 4.9 AV:N/AC:M/Au:S/C:P/I:P/A:N 6.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:N