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CVE-2021-26855

Known Exploited (CISA KEV)CRITICAL
9.1
CVSS Severity Score
EPSS Score77.9900%
EPSS Percentile90.51th
PublishedMar 3, 2021
Last ModifiedDec 18, 2025

Vulnerability Description

Microsoft Exchange Server Remote Code Execution Vulnerability

Affected Platforms (CPE)

📦
Microsoft

Exchange Server

= 2013
📦
Microsoft

Exchange Server

= 2013
📦
Microsoft

Exchange Server

= 2013
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2016
📦
Microsoft

Exchange Server

= 2019
📦
Microsoft

Exchange Server

= 2019
📦
Microsoft

Exchange Server

= 2019
📦
Microsoft

Exchange Server

= 2019
📦
Microsoft

Exchange Server

= 2019
📦
Microsoft

Exchange Server

= 2019
📦
Microsoft

Exchange Server

= 2019
📦
Microsoft

Exchange Server

= 2019
📦
Microsoft

Exchange Server

= 2019

References & Advisories

🔗 http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html
🔗 http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html
🔗 http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html
🔗 http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html
🔗 https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855
🔗 http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html
🔗 http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html
🔗 http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html

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