← Back to CVEs

CVE-2021-26855

CRITICALCISA KEV

9.1

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

CVE Details

CVSS v3.1 Score9.1

SeverityCRITICAL

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionNONE

Published3/3/2021

Last Modified12/18/2025

Sourcekev

Honeypot Sightings0

CISA KEV

VendorMicrosoft

ProductExchange Server

Vulnerability NameMicrosoft Exchange Server Remote Code Execution Vulnerability

KEV Date Added2021-11-03

Remediation Due Date2022-05-03

Ransomware UseKnown

Affected Products

microsoft:exchange_server

Weaknesses (CWE)

CWE-918CWE-918

References

http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html(secure@microsoft.com)

http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html(secure@microsoft.com)

http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html(secure@microsoft.com)

http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html(secure@microsoft.com)

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855(secure@microsoft.com)

http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html(af854a3a-2127-422b-91ae-364da2661108)

http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html(af854a3a-2127-422b-91ae-364da2661108)

http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html(af854a3a-2127-422b-91ae-364da2661108)

http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html(af854a3a-2127-422b-91ae-364da2661108)

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855(af854a3a-2127-422b-91ae-364da2661108)

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855(134c704f-9b21-4f2e-91b3-4a467353bcc0)

IOC Correlations

No correlations recorded

This product uses data from the NVD API but is not endorsed or certified by the NVD.