Server-Side Request Forgery (SSRF) in Microsoft Exchange Server - CVE-2021-26855
Published: March 2, 2021 / Updated: May 14, 2023
Vulnerability identifier: #VU51171
CSH Severity: Critical
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:N/SA:N/E:A/U:Red
CVE-ID: CVE-2021-26855
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vendor: Microsoft
Affected software:
Microsoft Exchange Server
Microsoft Exchange Server
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary code on the system.
The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send specially crafted HTTP request to the Microsoft Exchange OWA interface, upload arbitrary file on the server and execute it.
Note, this vulnerability is being actively exploited in the wild.
How to mitigate CVE-2021-26855
Install updates from vendor's website.