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How the mentioned CVE works:
This vulnerability stems from a lack of proper validation for device keys submitted by local users on a Synapse homeserver. An attacker registered on the server can submit invalid or malformed device keys. When the server attempts to use these keys during federation events, such as sending encrypted messages or verifying user identities with other homeservers, the invalid keys cause processing failures. This disrupts the outbound federation queue, leading to unpredictable and degraded communication. The federation connection to other Matrix homeservers may break, preventing message delivery and synchronization, effectively causing a denial-of-service for federated communications originating from the vulnerable server.
DailyCVE Form:
Platform: Synapse
Version: <1.138.3, 1.139.0rc1
Vulnerability: Federation Degradation
Severity: Moderate
Date: 2024-10-08
Prediction: 2024-10-15
What Undercode Say:
`curl -s https://api.github.com/repos/matrix-org/synapse/tags | jq ‘.[bash].name’`
`docker exec synapse grep ‘federation’ /homeserver.log`
`pip list | grep matrix-synapse`
How Exploit:
1. Register attacker account.
2. Upload invalid device keys.
3. Trigger federation activity.
4. Observe queue failures.
Protection from this CVE:
Upgrade to 1.138.4.
Upgrade to 1.139.2.
Isolate test instances.
Monitor federation queues.
Impact:
Federation message failure.
Inter-server communication break.
Partial denial-of-service.
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Sources:
Reported By: github.com
Extra Source Hub:
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