CRITICAL SECURITY UPDATE: Further details on the Synapse vulnerability affecting all versions prior to v0.34.1 (CVE-2019-5885) . Admins should upgrade immediately if they have not already done so. https://matrix.org/blog/2019/01/15/further-details-on-critical-security-update-in-synapse-affecting-all-versions-prior-to-0-34-1-cve-2019-5885/