Provide references for CVE-2021-39222.
Where can I find more information about CVE-2021-39222?
References are available at: https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xhxq-f4vg-jw5g, https://github.com/nextcloud/spreed/pull/542, https://hackerone.com/reports/1135481.