CVE-2021-26855

9.1 CRITICAL CISA KEV - Actively Exploited
Published: March 03, 2021 Modified: October 30, 2025
View on NVD

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html
Source: secure@microsoft.com
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html
Source: secure@microsoft.com
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html
Source: secure@microsoft.com
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html
Source: secure@microsoft.com
Exploit Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855
Source: secure@microsoft.com
Patch Vendor Advisory
http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855
Source: af854a3a-2127-422b-91ae-364da2661108
Patch Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
US Government Resource

11 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.1 / 10.0
EPSS (Exploit Probability)
94.4%
100th percentile
Exploitation Status
Actively Exploited
Remediation due: 2022-05-03

Weaknesses (CWE)

CWE-918 CWE-918

Affected Vendors

microsoft

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