AIKIDO-2026-262736
matrix-synapse is vulnerable to Information Disclosure
52
Medium Risk
This Affects:
matrix-synapseTL;DR
The federation timestamp_to_event endpoint does not verify that the requesting homeserver is in the room before responding. Any remote homeserver that knows a room ID can request the event nearest to a given timestamp and receive event IDs. This unintentionally discloses event IDs from rooms the requesting server has not joined. The fix verifies room membership before handling the request.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and your homeserver participates in open federation.
Background info
matrix-synapse is vulnerable to Information Disclosure in versions 0.0.1 - 1.157.1.
How to fix this
Upgrade the matrix-synapse library to the patch version.
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SOC 2Compliant
ISO 27001Compliant