PT-2021-3816 · Microsoft · Exchange Server

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

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 (affected versions not specified)

Description An elevation of privilege issue exists in Microsoft Exchange Server. This flaw allows an attacker to increase their privilege level on the system. Additionally, improper authentication in PowerShell may lead to remote code execution, which allows an attacker to execute arbitrary commands on the server from a remote location.

Recommendations 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-264

CWE-287

Related Identifiers

BDU:2021-04126

CVE-2021-34523

ZDI-21-822

Affected Products

Exchange Server

References · 93

• 🔥 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://bdu.fstec.ru/vul/2021-04126 · Security Note
• 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://zerodayinitiative.com/advisories/ZDI-21-822 · 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
• https://safe-surf.ru/specialists/bulletins-nkcki/667108 · Security Note
• https://t.me/aptreports/1885 · Telegram Post
• https://t.me/aptreports/1920 · Telegram Post
• https://t.me/aptreports/11574 · Telegram Post
• https://twitter.com/fletch_ai/status/1750309302198268365 · Twitter Post