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Status published
Critical
CVE-2021-26855
Microsoft Exchange Server Remote Code Execution Vulnerability
Vulnerability Description
Microsoft Exchange Server Remote Code Execution Vulnerability
Impact Analysis
Refer to official advisory for detailed impact metrics.
Remediation
Ensure systems are updated to the latest vendor-supplied patch levels.
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Credits & Attribution
No credits recorded in the NVD database.
References
- 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
- http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html
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Affected Vendor
Microsoft
View all reports →Affected Software
Microsoft Exchange Server 2016 Cumulative Update 19, Microsoft Exchange Server 2019 Cumulative Update 8, Microsoft Exchange Server 2019, Microsoft Exchange Server 2013 Cumulative Update 22, Microsoft Exchange Server 2019 Cumulative Update 2, Microsoft Exchange Server 2016 Cumulative Update 13, Microsoft Exchange Server 2013 Cumulative Update 23, Microsoft Exchange Server 2019 Cumulative Update 3, Microsoft Exchange Server 2016 Cumulative Update 14, Microsoft Exchange Server 2019 Cumulative Update 4, Microsoft Exchange Server 2016 Cumulative Update 15, Microsoft Exchange Server 2019 Cumulative Update 5, Microsoft Exchange Server 2019 Cumulative Update 6, Microsoft Exchange Server 2016 Cumulative Update 16, Microsoft Exchange Server 2016 Cumulative Update 17, Microsoft Exchange Server 2019 Cumulative Update 7, Microsoft Exchange Server 2016 Cumulative Update 18, Microsoft Exchange Server 2013 Cumulative Update 21, Microsoft Exchange Server 2016 Cumulative Update 12, Microsoft Exchange Server 2016 Cumulative Update 8, Microsoft Exchange Server 2019 Cumulative Update 1, Microsoft Exchange Server 2016 Cumulative Update 9, Microsoft Exchange Server 2016 Cumulative Update 10, Microsoft Exchange Server 2016 Cumulative Update 11
Vulnerable Versions:
15.01.0, 15.02.0, 15.00.0
Timeline
Official Publish:
March 2nd, 2021
Last Modified:
October 21st, 2025
Added to House:
July 21st, 2026
CVSS Vectors
V3:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:F/RL:O/RC:C
Weaknesses (CWE)
No CWE data available
MITRE ATT&CK TTPs
No associated TTPs found for this vulnerability.