Zero-day vulnerability in Microsoft Exchange Server

Input validation error

Vulnerability details

Advisory: SB2021030301 - Multiple vulnerabilities in Microsoft Exchange Server

Vulnerable component: Microsoft Exchange Server

CVE-ID: CVE-2021-26858

CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-20 - Improper input validation


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 data to the Exchange server and execute arbitrary code on the system.

Note, this vulnerability is being actively exploited in the wild.