| CVE-2021-21392 | Date: (C)2021-04-15 (M)2023-12-22 |
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.
CVSS Score and Metrics +CVSS Score and Metrics -| CVSS V3 Severity: | CVSS V2 Severity: |
| CVSS Score : 6.3 | CVSS Score : 4.9 |
| Exploit Score: 2.1 | Exploit Score: 6.8 |
| Impact Score: 4.2 | Impact Score: 4.9 |
| |
| CVSS V3 Metrics: | CVSS V2 Metrics: |
| Attack Vector: NETWORK | Access Vector: NETWORK |
| Attack Complexity: LOW | Access Complexity: MEDIUM |
| Privileges Required: LOW | Authentication: SINGLE |
| User Interaction: REQUIRED | Confidentiality: PARTIAL |
| Scope: UNCHANGED | Integrity: PARTIAL |
| Confidentiality: LOW | Availability: NONE |
| Integrity: HIGH | |
| Availability: NONE | |
| | |
