Provide references for CVE-2021-26855.
Where can I find more information about CVE-2021-26855?
References are available at: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855, http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html, http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html, http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html, http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html.