CVE-2021-27065 — Microsoft Exchange Server Remote Code Execution Vulnerability
Overview
Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.
Vulnerability details
- CVE ID
- CVE-2021-27065
- Vulnerability
- Microsoft Exchange Server Remote Code Execution Vulnerability
- Vendor
- Microsoft
- Affected products
- Microsoft: Exchange Server
- Severity
- HIGH
- Exploitation status
- Actively exploited in the wild (CISA KEV)
- Published
- 2021-11-03
Remediation guidance
CVE-2021-27065 is in CISA's Known Exploited Vulnerabilities (KEV) catalog — U.S. federal civilian agencies are required to remediate it under Binding Operational Directive 22-01. Treat it as a priority for every environment.
Apply the vendor's official security update for Microsoft the affected product as soon as possible. Where a patch is unavailable, apply vendor mitigations or isolate/segment exposed systems.
Hunt for indicators of compromise tied to this vulnerability and confirm logging/EDR coverage on affected assets.
Authoritative references
Remediate CVE-2021-27065 — and stay ahead of the next one
CVE-2021-27065 is listed in the CISA KEV catalog as actively exploited — treat remediation as urgent. Scan your domain free to see whether CVE-2021-27065 and other Microsoft issues affect you and get a prioritized remediation report (full report from ₹999) — or stream the full feed of 1,600+ actively-exploited CVEs straight into your SOC.
📡 Get a free alert the moment a CVE like this lands in the KEV catalog → Join Sentinel APEX on Telegram