Matrix Synapse before 0.34.0.1, when the macaroonsecretkey authentication parameter is not set, uses a predictable value to derive a secret key and other secrets which could allow remote attackers to impersonate users.
{ "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro", "ubuntu_priority": "medium", "binaries": [ { "binary_version": "0.24.0+dfsg-1ubuntu0.1~esm1", "binary_name": "matrix-synapse" } ] }