CVE-2021-27065
Microsoft Exchange Server Remote Code Execution Vulnerability
Microsoft · Exchange Server
Vulnerability details
Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.
Added to CISA KEV: 2021-11-03
Ransomware campaign use: Known
CISA due date: 2022-05-03
Defensive guidance from CISA
Apply updates per vendor instructions.
This is the source's required-action field, not an independently validated patch procedure. Refer to the vendor for exact affected versions and fixes.
Source catalog date: 2026-11-06T19:44:45.1797Z · Last retrieved: 2026-11-06 21:02:26 UTC