CVE-2022-21855: Microsoft Exchange Server Remote Code Execution Vulnerability

Overview

Severity
Critical (CVSS 9)
CVSS Vector
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Remote Code Execution
Exploit Status
Not Exploited
Exploitation Likelihood
More Likely
Patch Tuesday
2022-Jan
Released
2022-01-11
EPSS Score
1.53% (percentile: 81.3%)

FAQ

According to the CVSS metric, the attack vector is adjacent (AV:A). What does that mean for this vulnerability? This vulnerability's attack is limited at the protocol level to a logically adjacent topology. This means it cannot simply be done across the internet, but instead needs something specific tied to the target. Good examples would include the same shared physical network (such as Bluetooth or IEEE 802.11), logical network (local IP subnet), or from within a secure or otherwise limited administrative domain (MPLS, secure VPN to an administrative network zone). This is common to many attacks that require machine-in-the-middle (MITM) type setups or that rely on initially gaining a foothold in another environment.

Affected Products (5)

Server Software

  • Microsoft Exchange Server 2013 Cumulative Update 23
  • Microsoft Exchange Server 2016 Cumulative Update 21
  • Microsoft Exchange Server 2019 Cumulative Update 10
  • Microsoft Exchange Server 2016 Cumulative Update 22
  • Microsoft Exchange Server 2019 Cumulative Update 11

Security Updates (5)

Acknowledgments

<a href="https://twitter.com/arudd1ck">Andrew Ruddick</a>, Microsoft Security Response Center

Revision History

  • 2022-01-11: Information published.