Zulip - 5.3

5.3 -- 2022-06-21

• CVE-2022-31017: Fixed message edit event exposure in
  protected-history streams.
  Zulip allows a stream to be configured as private with protected
  history,
  which means that new subscribers should only see messages sent after
  they join. However, due to a logic bug in Zulip Server 2.1.0 through
  5.2, when a message was edited, the server would incorrectly send an
  API event that included both the edited and old content of the
  message to all of the stream’s current subscribers, regardless of
  whether they could see the original message. The impact of this
  issue was reduced by the fact that this API event is ignored by
  official clients, so it could only be observed by a user using a
  modified client or their browser’s developer tools.
• Adjusted upgrade steps to cause servers using PostgreSQL 14 to
  upgrade to PostgreSQL 14.4, which fixes an important potential
  database corruption issue.
• Upgraded the asynchronous request handling to use Tornado 6.
• Fixed a crash when displaying the error message for a failed attempt
  to create a stream.
• Optimized the steps during upgrade-zulip, to reduce the amount of
  server downtime.
• Added a --skip-restart flag to upgrade-zulip which prepares the
  new version, but does not restart the server into it.
• Stopped mirroring the entire remote Git repository directly into
  /srv/zulip.git. This mirroring removed local branches and confused
  the state of previous deployments.
• Fixed a bug which could cause the delete_old_unclaimed_attachments
  command-line tool to remove attachments that were still referenced
  by deleted (but not yet permanently removed) messages.
• Stopped enabling USE_X_FORWARDED_HOST by default, which was
  generally unneeded; the proxy documentation now clarifies when it is
  necessary.
• Fixed the nginx configuration to include the default system-level
  nginx modules.
• Only attempt to fix the certbot SSL renewal configuration if HTTPS
  is enabled; this addresses a regression in Zulip Server 5.2, where
  the upgrade would fail if an improperly configured certificate
  existed, but was both expired and not in use.
• Improved proxy and database backup documentation.