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CVE-2021-21274
Good to know:
Date: February 26, 2021
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 1.25.0, a malicious homeserver could redirect requests to their .well-known file to a large file. This can lead to a denial of service attack where homeservers will consume significantly more resources when requesting the .well-known file of a malicious homeserver. This affects any server which accepts federation requests from untrusted servers. Issue is resolved in version 1.25.0. As a workaround the "federation_domain_whitelist" setting can be used to restrict the homeservers communicated with over federation.
Language: Python
Severity Score
Related Resources (10)
Severity Score
Weakness Type (CWE)
Top Fix
CVSS v3.1
| Base Score: |
|
|---|---|
| Attack Vector (AV): | NETWORK |
| Attack Complexity (AC): | LOW |
| Privileges Required (PR): | NONE |
| User Interaction (UI): | REQUIRED |
| Scope (S): | UNCHANGED |
| Confidentiality (C): | NONE |
| Integrity (I): | NONE |
| Availability (A): | LOW |
CVSS v2
| Base Score: |
|
|---|---|
| Access Vector (AV): | NETWORK |
| Access Complexity (AC): | MEDIUM |
| Authentication (AU): | NONE |
| Confidentiality (C): | NONE |
| Integrity (I): | NONE |
| Availability (A): | PARTIAL |
| Additional information: |