Prosody -- multiple vulnerabilities

The Prosody security advisory 2021-05-12 reports:

    This advisory details 5 new security vulnerabilities discovered in the
    Prosody.im XMPP server software. All issues are fixed in the 0.11.9
    release default configuration.

CVE-2021-32918: DoS via insufficient memory consumption controls
CVE-2021-32920: DoS via repeated TLS renegotiation causing excessive CPU consumption
CVE-2021-32921: Use of timing-dependent string comparison with sensitive values
CVE-2021-32917: Use of mod_proxy65 is unrestricted in default configuration
CVE-2021-32919: Undocumented dialback-without-dialback option insecure