⚠ Actively exploited in ransomware campaigns
This vulnerability is on the CISA Known Exploited Vulnerabilities list and has been used in known ransomware attacks. CISA required action: Apply updates per vendor instructions.. Due date: 2021-11-17.

CVE-2021-34473

CWE-918 — Server-Side Request Forgery (SSRF)22 documents14 sources
Severity
9.8CRITICAL
EPSS
94.2%
top 0.08%
CISA KEV
KEVRansomware
Added 2021-11-03
Due 2021-11-17
Exploit
Exploited in wild
Active exploitation observed
Affected products
6
Microsoft Microsoft Exchange Server 2013 Cumulative Update 23Microsoft Microsoft Exchange Server 2016 Cumulative Update 19Microsoft Microsoft Exchange Server 2016 Cumulative Update 20+3 more
Timeline
PublishedJul 14
KEV addedNov 3
KEV dueNov 17
Latest updateJul 30
CISA Required Action: Apply updates per vendor instructions.

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NExploitability: 3.9 | Impact: 5.2

Affected Packages6 packages

Patches

Patch: portal.msrc.microsoft.com ↗Patch: portal.msrc.microsoft.com ↗

🔴Vulnerability Details

3
GHSA
GHSA-fgq9-p33g-xcfc: Microsoft Exchange Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-31196, CVE-2021-31206↗2022-05-24
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CVEList
Microsoft Exchange Server Remote Code Execution Vulnerability↗2021-07-14
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VulnCheck
Microsoft Exchange Server Remote Code Execution Vulnerability↗2021
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💥Exploits & PoCs

2
Nuclei
Exchange Server - Remote Code Execution
▶
Metasploit
Microsoft Exchange ProxyShell RCE↗
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🔍Detection Rules

5
Suricata
ET EXPLOIT Possible Microsoft Exchange Mailbox Enumeration Inbound (CVE-2021-34473)↗2022-03-29
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Suricata
ET EXPLOIT Possible Microsoft Exchange RCE Inbound M3 (CVE-2021-34473)↗2022-03-29
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Suricata
ET EXPLOIT Possible Microsoft Exchange RCE Inbound M2 (CVE-2021-34473)↗2021-08-12
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Suricata
ET EXPLOIT Possible Microsoft Exchange RCE with Python PSRP Client UA Inbound (CVE-2021-34473)↗2021-08-12
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Suricata
ET EXPLOIT Possible Microsoft Exchange RCE Inbound M1 (CVE-2021-34473)↗2021-08-09
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📋Vendor Advisories

2
CISA
Microsoft Exchange Server Remote Code Execution Vulnerability↗2021-11-03
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Microsoft
Microsoft Exchange Server Remote Code Execution Vulnerability↗2021-07-13
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🕵️Threat Intelligence

5
Bleepingcomputer
UK govt links 2021 Electoral Commission breach to Exchange server↗2024-07-30
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Unit42
Manic Menagerie 2.0: The Evolution of a Highly Motivated Threat Actor↗2023-06-28
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Unit42
Top CVEs to Patch: Insights from the 2022 Unit 42 Network Threat Trends Research Report↗2022-07-21
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Elastic
Detection and response for the actively exploited ProxyShell vulnerabilities — Elastic Security Labs↗2022-06-02
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Unit42
Network Security Trends: August-October 2021↗2021-12-21
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CVE-2021-34473 (CRITICAL CVSS 9.8) | Microsoft Exchange Server Remote Co | cvebase.io