PT-2021-3816 · Microsoft · Exchange Server

Orangetw · Published 2021-07-13 · Updated 2026-05-20 · CVE-2021-34523

Positive Technologies (AI Summary)

CVSS v3.1

9.0

Critical

Base vector

AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

Name of the Vulnerable Software and Affected Versions Microsoft Exchange Server versions 2013 through 2019

Description The issue is related to errors in privilege management, allowing an attacker to elevate their privileges. This can affect the system and potentially lead to remote code execution due to improper authentication in Microsoft Exchange Server's PowerShell.

Recommendations For Microsoft Exchange Server versions 2013 through 2019, consider restricting access to the PowerShell module to minimize the risk of exploitation until a patch is available. As a temporary workaround, consider disabling the vulnerable authentication mechanism in the PowerShell interface until a fix is provided. At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Exploit

LPE

Improper Authentication

Weakness Enumeration

CWE-287

CWE-264

Related Identifiers

BDU:2021-04126

CVE-2021-34523

ZDI-21-822

Affected Products

Exchange Server

References · 92

• 🔥 https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/windows/http/exchange_proxyshell_rce.rb · Exploit
• 🔥 https://github.com/mithridates1313/ProxyShell_POC · Exploit
• 🔥 http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html · Exploit
• https://zerodayinitiative.com/advisories/ZDI-21-822 · Security Note
• https://bdu.fstec.ru/vul/2021-04126 · Security Note
• https://safe-surf.ru/specialists/bulletins-nkcki/667108 · Security Note
• https://osv.dev/vulnerability/CVE-2021-34523 · Vendor Advisory
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34523 · Vendor Advisory
• https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-34523 · Vendor Advisory
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-34523 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2021-34523 · Security Note
• https://cybersecurity-help.cz/vdb/SB2021071319 · Note
• https://t.me/true_secator/1917 · Telegram Post
• https://t.me/aptreports/1885 · Telegram Post
• https://t.me/aptreports/4709 · Telegram Post