Actively exploited · Published Jul 14, 2021 · Assigned by microsoft
CVE-2021-34473Microsoft Exchange Server Remote Code Execution Vulnerability
Critical 9.1 Exploited Ransomware
In plain English
A critical-severity server-side request forgery in Microsoft Exchange Server 2013 Cumulative Update 23 from Microsoft. Attackers are actively exploiting it in the wild (listed by CISA on November 3, 2021). It has been used in ransomware campaigns. The chance it is exploited in the next 30 days is estimated at 100.0% (higher than 99.9% of all known vulnerabilities). Ready-made attack tooling exists: Metasploit, Nuclei, public proof-of-concept code. Apply updates per vendor instructions.
CISA guidance
Apply updates per vendor instructions.
Federal agencies must remediate by Nov 17, 2021.
Official description
Microsoft Exchange Server Remote Code Execution Vulnerability
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft Exchange Server 2013 Cumulative Update 23 | 15.00.0 – before 15.00.1497.015 |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 19 | 15.01.0 – before 15.01.2176.012 |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 20 | 15.01.0 – before 15.01.2242.008 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 8 | 15.02.0 – before 15.02.0792.013 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 9 | 15.02.0 – before 15.02.0858.010 |
Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C
References
- Microsoft Exchange Server Remote Code Execution Vulnerability vendor-advisory, patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34473 x_refsource_MISC, x_transferred
- https://www.zerodayinitiative.com/advisories/ZDI-21-821/ x_refsource_MISC, x_transferred
- http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html x_refsource_MISC, x_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34473 government-resource