6.3
CVSSv3

CVE-2021-21392

Published: 12/04/2021 Updated: 07/11/2023
CVSS v2 Base Score: 4.9 | Impact Score: 4.9 | Exploitability Score: 6.8
CVSS v3 Base Score: 6.3 | Impact Score: 4.2 | Exploitability Score: 2.1
VMScore: 436
Vector: AV:N/AC:M/Au:S/C:P/I:P/A:N

Vulnerability Summary

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.

Vulnerability Trend

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matrix synapse

fedoraproject fedora 34