Input validation error in Microsoft Exchange Server - CVE-2021-42321
Published: November 9, 2021 / Updated: November 16, 2022
Vulnerability identifier: #VU58055
CSH Severity: Critical
CVSS v4: 9.4 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H]
CVE-ID: CVE-2021-42321
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vulnerability details
The vulnerability allows a remote user to compromise the affected system.
The vulnerability exists due to insufficient validation of cmdlet arguments. A remote user can run a specially crafted cmdlet and execute arbitrary commands on the system.
Note, the vulnerability is being actively exploited in the wild.
Affected software
Microsoft Exchange Server
How to mitigate CVE-2021-42321
Install updates from vendor's website.
Links to Public Exploits and PoC-codes
- Exploit #8613 - exch_CVE-2021-42321 () (November 16, 2022)
- Exploit #8267 - Microsoft Exchange Server ChainedSerializationBinder RCE (August 19, 2022)
- Exploit #7772 - Microsoft Exchange Server ChainedSerializationBinder Deny List Typo RCE (May 12, 2022)
- Exploit #7224 - CVE-2021-42321_poc () (January 6, 2022)