CVE-2021-41349 — Microsoft Exchange Server Spoofing Vulnerability

Executive Summary

None

Overview

6.5

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Spoofing

Released Nov 9 2021

Last Updated Nov 9 2021

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.93877 — 0.99836 percentile

NVD CVSS 6.5 MEDIUM — matches MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

Required

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

None

AVAILABILITY

None

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 5.7

EPSS Score

0.93877

probability of exploitation in the next 30 days

0.99836 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

5 affected products

Product	KB Article	Severity	Impact	Restart Required
Microsoft Exchange Server 2013 Cumulative Update 23	`5007409 (Security Update)`	Important	Spoofing	Yes
Microsoft Exchange Server 2016 Cumulative Update 21	`5007409 (Security Update)`	Important	Spoofing	Yes
Microsoft Exchange Server 2016 Cumulative Update 22	`5007409 (Security Update)`	Important	Spoofing	Yes
Microsoft Exchange Server 2019 Cumulative Update 10	`5007409 (Security Update)`	Important	Spoofing	Yes
Microsoft Exchange Server 2019 Cumulative Update 11	`5007409 (Security Update)`	Important	Spoofing	Yes

Patches

1 patch

Article	Type	Restart
`5007409`	Security Update	Yes

Exploits & PoC

2 public PoCs

Unverified third-party code

Public proof-of-concept repositories aggregated from PoC-in-GitHub. They are not reviewed and may be incomplete, non-functional, or malicious — inspect the code before running anything.

Repository	Stars	Published	Description
exploit-io/CVE-2021-41349	11	2022-01-06	Exploiting: CVE-2021-41349
0xrobiul/CVE-2021-41349	4	2022-07-30	Microsoft Exchange Server Spoofing Vulnerability Exploit!

Detection Rules

Detection available

Community detection & vulnerability-scanning rules aggregated from Sigma and Nuclei templates. Validate and tune to your environment before deploying.

Nuclei templates 1

CVE-2021-41349 Microsoft Exchange Server Pre-Auth POST Based Cross-Site Scripting medium

nuclei -id CVE-2021-41349

Acknowledgments

Ashish Kunwar
Wabaf3t
Rahul Maini with SecAid
MIke Xie
Tony Zhan with Dell
Sainath Reddy
Thomas Spring with Swisscom (Schweiz) AG
Harsh and Rahul with HTTPVoid
Olga Sviridova with Ecommpay

References

MSRC Advisory MITRE NVD