Microsoft Exchange Server Authentication Bypass

critical Nessus Plugin ID 147171

Synopsis

The remote mail server is affected by an authentication bypass vulnerability.

Description

The Microsoft Exchange running on the remote host is affected by an authentication bypass vulnerability. An unauthenticated remote attacker can exploit this to execute arbitrary code.

Solution

Microsoft has released the following security updates to address this issue:
-KB5000871

See Also

http://www.nessus.org/u?14b26c05

http://www.nessus.org/u?fedb98e4

http://www.nessus.org/u?d9bf7dee

https://proxylogon.com/

http://www.nessus.org/u?4260a57a

Plugin Details

Severity: Critical

ID: 147171

File Name: exchange_cve-2021-26855.nbin

Version: 1.34

Type: remote

Agent: windows

Family: Windows

Published: 3/8/2021

Updated: 8/31/2022

Supported Sensors: Nessus Agent

Risk Information

VPR

Risk Factor: Critical

Score: 9.8

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P

Temporal Vector: E:H/RL:OF/RC:C

CVSS Score Source: CVE-2021-26855

CVSS v3

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: E:H/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:microsoft:exchange_server

Required KB Items: installed_sw/Exchange Server

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 3/2/2021

Vulnerability Publication Date: 3/2/2021

CISA Known Exploited Dates: 4/16/2021

Exploitable With

CANVAS (CANVAS)

Metasploit (Microsoft Exchange ProxyLogon RCE)

Reference Information

CVE: CVE-2021-26855

MSKB: 5000871

MSFT: MS21-5000871

CISA-NCAS: AA22-011A