Provide references for CVE-2021-39223.
Where can I find more information about CVE-2021-39223?
References are available at: https://github.com/nextcloud/security-advisories/security/advisories/GHSA-rjcc-4cgj-6v93, https://github.com/nextcloud/richdocuments/pull/1760, https://hackerone.com/reports/1253460.