Known Exploited Vulnerability
8.8
HIGH
CVE-2021-42321
Microsoft Exchange Server Remote Code Execution Vu - [Actively Exploited]
Description

Microsoft Exchange Server Remote Code Execution Vulnerability

INFO

Published Date :

Nov. 10, 2021, 1:19 a.m.

Last Modified :

March 7, 2025, 9:54 p.m.

Remotely Exploitable :

Yes !

Impact Score :

5.9

Exploitability Score :

2.8
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

Description :

An authenticated attacker could leverage improper validation in cmdlet arguments within Microsoft Exchange and perform remote code execution.

Required Action :

Apply updates per vendor instructions.

Notes :

https://nvd.nist.gov/vuln/detail/CVE-2021-42321

Public PoC/Exploit Available at Github

CVE-2021-42321 has a 45 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

Affected Products

The following products are affected by CVE-2021-42321 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Microsoft exchange_server
References to Advisories, Solutions, and Tools

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

exchange工具

Python C# PowerShell HTML

Updated: 3 months, 2 weeks ago
0 stars 0 fork 0 watcher
Born at : Dec. 16, 2024, 6:56 a.m. This repo has been linked 3 different CVEs too.

oscp notes

Updated: 3 months, 2 weeks ago
0 stars 0 fork 0 watcher
Born at : Dec. 9, 2024, 6:26 p.m. This repo has been linked 66 different CVEs too.

None

C#

Updated: 4 months ago
1 stars 0 fork 0 watcher
Born at : Nov. 29, 2024, 3:14 p.m. This repo has been linked 17 different CVEs too.

This repository is designed to provide a comprehensive collection of study materials, notes, and resources for the Offensive Security Certified Professional (OSCP) exam. It covers all key topics from basic to advanced, helping aspiring penetration testers to prepare efficiently for the exam.

cybersecurity hacking oscp oscp-guide oscp-journey oscp-prep

Updated: 2 months, 2 weeks ago
6 stars 1 fork 1 watcher
Born at : Oct. 4, 2024, 4:43 p.m. This repo has been linked 75 different CVEs too.

None

Python C Shell PHP PowerShell ASP.NET

Updated: 3 months, 2 weeks ago
0 stars 0 fork 0 watcher
Born at : Oct. 1, 2024, 2:21 p.m. This repo has been linked 66 different CVEs too.

None

C#

Updated: 6 months, 4 weeks ago
0 stars 0 fork 0 watcher
Born at : Sept. 3, 2024, 7:41 p.m. This repo has been linked 17 different CVEs too.

OSCP and stuffs

Updated: 7 months, 2 weeks ago
1 stars 0 fork 0 watcher
Born at : April 19, 2024, 8:18 p.m. This repo has been linked 63 different CVEs too.

Resources to learn about Insecure Deserialization

Updated: 2 months, 2 weeks ago
6 stars 0 fork 0 watcher
Born at : April 17, 2024, 7 p.m. This repo has been linked 20 different CVEs too.

None

Python C Shell

Updated: 8 months, 2 weeks ago
1 stars 0 fork 0 watcher
Born at : March 29, 2024, 5:29 a.m. This repo has been linked 62 different CVEs too.

All CVE - PoC in GitHub

poc proofofconcept tester allcve cvegithub cvenew cvepoc cveupdate

Updated: 3 months, 2 weeks ago
9 stars 3 fork 3 watcher
Born at : March 22, 2024, 3:58 p.m. This repo has been linked 931 different CVEs too.

None

Updated: 1 year ago
1 stars 0 fork 0 watcher
Born at : March 11, 2024, 1:21 p.m. This repo has been linked 933 different CVEs too.

OffSec Certified Professional Certification (OSCP).

oscp oscp-cheatsheet oscp-guide oscp-journey oscp-prep oscp-tools offsec-certified-professional-certification offensive-security offensivesecurity awesome-list awesome-lists cheatsheet offensive-ops

Updated: 1 year ago
1 stars 1 fork 1 watcher
Born at : March 5, 2024, 9:21 a.m. This repo has been linked 61 different CVEs too.

Oscp-notes

Updated: 7 months, 2 weeks ago
1 stars 0 fork 0 watcher
Born at : March 3, 2024, 5:12 a.m. This repo has been linked 61 different CVEs too.

None

Updated: 2 months ago
1 stars 0 fork 0 watcher
Born at : Feb. 27, 2024, 3:28 p.m. This repo has been linked 22 different CVEs too.

None

C#

Updated: 1 year, 1 month ago
0 stars 0 fork 0 watcher
Born at : Feb. 25, 2024, 3:15 p.m. This repo has been linked 17 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-42321 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2021-42321 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Modified Analysis by [email protected]

    Mar. 07, 2025

    Action Type Old Value New Value
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.html
    Added Reference http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.html
    Added Reference https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321
  • Modified Analysis by [email protected]

    Jul. 24, 2024

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    Dec. 28, 2023

    Action Type Old Value New Value
    Added CVSS V3.1 Microsoft Corporation AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  • Modified Analysis by [email protected]

    Aug. 29, 2022

    Action Type Old Value New Value
    Changed Reference Type http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.html No Types Assigned http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.html Exploit, Third Party Advisory, VDB Entry
  • CVE Modified by [email protected]

    Aug. 22, 2022

    Action Type Old Value New Value
    Added Reference http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.html [No Types Assigned]
  • CWE Remap by [email protected]

    Jul. 12, 2022

    Action Type Old Value New Value
    Changed CWE NVD-CWE-noinfo NVD-CWE-Other
  • Modified Analysis by [email protected]

    Mar. 29, 2022

    Action Type Old Value New Value
    Changed Reference Type http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.html No Types Assigned http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.html Exploit, Third Party Advisory, VDB Entry
  • CVE Modified by [email protected]

    Feb. 25, 2022

    Action Type Old Value New Value
    Added Reference http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.html [No Types Assigned]
  • Initial Analysis by [email protected]

    Nov. 10, 2021

    Action Type Old Value New Value
    Added CVSS V2 NIST (AV:N/AC:L/Au:S/C:P/I:P/A:P)
    Added CVSS V3.1 NIST AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    Changed Reference Type https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321 No Types Assigned https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321 Patch, Vendor Advisory
    Added CWE NIST NVD-CWE-noinfo
    Added CPE Configuration OR *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_21:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_22:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_10:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_11:*:*:*:*:*:*
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-42321 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-42321 weaknesses.

Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

93.16 }} -0.14%

score

0.99792

percentile

CVSS31 - Vulnerability Scoring System
Attack Vector
Attack Complexity
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Scope
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Integrity
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