CVE-2021-34473
Microsoft Exchange Server Remote Code Execution Vulnerability
This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Exchange Server, fix it now.
CISA required action: Apply updates per vendor instructions.
US federal civilian agencies must remediate by Nov 17, 2021.
Patch status
Official fix available since
Apply the vendor's update to every affected system. Check the fixed-in versions below where known.
Basis: NVD patch reference
Description
Microsoft Exchange Server Remote Code Execution Vulnerability
Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.
Affected products
| Product | Vendor | Affected versions | Source |
|---|---|---|---|
| Exchange Server | Microsoft | 2013; 2016; 2019 | KEV |
Sources: KEV = CISA Known Exploited Vulnerabilities catalog.
Intelligence timeline
Developments from the last 30 days, newest first.
- CVSS scoredUpdateKEV
CVE-2021-34473 scored CVSS 9.1: Microsoft Exchange Server, Microsoft Exchange Server Remote Code Execution Vulnerability
CISA lists this as exploited in the wild and known to be used in ransomware campaigns. Unpatched Exchange Server systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
- Patch releasedUpdateKEV
Patch released for CVE-2021-34473: Microsoft Exchange Server, Microsoft Exchange Server Remote Code Execution Vulnerability
An official fix is now available for Microsoft Exchange Server. This vulnerability is being exploited, so apply it promptly.
Basis: NVD patch reference
1 earlier event is available with a subscription. See plans.
Coverage
We have not published a story about this vulnerability yet.