Security Updates for Microsoft Exchange Server (April 2021)

critical Nessus Plugin ID 148476


The Microsoft Exchange Server installed on the remote host is affected by multiple vulnerabilities.


The Microsoft Exchange Server installed on the remote host is missing security updates. It is, therefore, affected by multiple vulnerabilities:

- A remote code execution vulnerability. An attacker could exploit this to execute unauthorized arbitrary code. (CVE-2021-28483, CVE-2021-28482, CVE-2021-28481, CVE-2021-28480, CVE-2021-34473)

- An elevation of privilege vulnerability. An attacker can exploit this to gain elevated privileges. (CVE-2021-34523)

- An information disclosure vulnerability. An attacker can exploit this to disclose potentially sensitive information. (CVE-2021-33766)


Microsoft has released the following security updates to address this issue:

See Also

Plugin Details

Severity: Critical

ID: 148476

File Name: smb_nt_ms21_apr_exchange.nasl

Version: 1.15

Type: local

Agent: windows

Published: 4/13/2021

Updated: 1/4/2024

Supported Sensors: Frictionless Assessment Agent, Nessus

Risk Information


Risk Factor: Critical

Score: 9.7


Risk Factor: Critical

Base Score: 10

Temporal Score: 8.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2021-34473


Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9.4

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:H/RL:O/RC:C

CVSS Score Source: CVE-2021-28481

Vulnerability Information

CPE: cpe:/a:microsoft:exchange_server

Required KB Items: SMB/MS_Bulletin_Checks/Possible

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/13/2021

Vulnerability Publication Date: 4/13/2021

CISA Known Exploited Vulnerability Due Dates: 11/17/2021, 2/1/2022

Exploitable With

Core Impact

Metasploit (Microsoft Exchange ProxyShell RCE)

Reference Information

CVE: CVE-2021-28480, CVE-2021-28481, CVE-2021-28482, CVE-2021-28483, CVE-2021-33766, CVE-2021-34473, CVE-2021-34523

IAVA: 2021-A-0160-S

MSFT: MS21-5001779

MSKB: 5001779