CVE-2021-26855

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2021-26855
Microsoft Exchange Server Remote Code Execution Vulnerability

9.1 /10

CVSS v3 : CRITICAL

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

7.5 /10

CVSS v2.0 : HIGH

V2 Legend

Vector : AV:N/AC:L/Au:N/C:P/I:P/A:P

Exploitability : 10.0 / Impact : 6.4

Access Vector NETWORK

Access Complexity LOW

Authentication NONE

Confidentiality Impact PARTIAL

Integrity Impact PARTIAL

Availability Impact PARTIAL

References
Link Resource
http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html Exploit Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855 Patch Vendor Advisory
http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html Exploit Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855 Patch Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855 US Government Resource
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_21:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_22:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_10:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_11:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_12:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_13:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_14:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_15:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_16:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_17:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_18:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_8:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_9:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:-:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_1:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_2:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_3:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_4:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_5:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_6:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_7:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:*
History

30 Oct 2025, 19:55

Type Values Removed Values Added
References () https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855 - () https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855 - US Government Resource

22 Oct 2025, 00:17

Type Values Removed Values Added
References
  • () https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855 -

21 Oct 2025, 20:18

Type Values Removed Values Added
References
  • {'url': 'https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855', 'source': '134c704f-9b21-4f2e-91b3-4a467353bcc0'}

21 Oct 2025, 19:18

Type Values Removed Values Added
References
  • () https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855 -

21 Nov 2024, 05:56

Type Values Removed Values Added
References () http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html - Exploit, Third Party Advisory, VDB Entry () http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html - Exploit, Third Party Advisory, VDB Entry
References () http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html - Exploit, Third Party Advisory, VDB Entry () http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html - Exploit, Third Party Advisory, VDB Entry
References () http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html - Exploit, Third Party Advisory, VDB Entry () http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html - Exploit, Third Party Advisory, VDB Entry
References () http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html - Exploit, Third Party Advisory, VDB Entry () http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html - Exploit, Third Party Advisory, VDB Entry
References () https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855 - Patch, Vendor Advisory () https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855 - Patch, Vendor Advisory

29 Dec 2023, 17:16

Type Values Removed Values Added
CVSS v2 : 7.5
v3 : 9.8 		v2 : 7.5
v3 : 9.1
Summary Microsoft Exchange Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26412, CVE-2021-26854, CVE-2021-26857, CVE-2021-26858, CVE-2021-27065, CVE-2021-27078. Microsoft Exchange Server Remote Code Execution Vulnerability

12 Jul 2022, 17:42

Type Values Removed Values Added
CWE NVD-CWE-noinfo CWE-918

06 May 2022, 20:57

Type Values Removed Values Added
References (MISC) http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html - (MISC) http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html - Exploit, Third Party Advisory, VDB Entry

21 May 2021, 18:15

Type Values Removed Values Added
References
  • (MISC) http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html -

21 May 2021, 16:52

Type Values Removed Values Added
References (MISC) http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html - (MISC) http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html - Exploit, Third Party Advisory, VDB Entry
References (MISC) http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html - Exploit, Third Party Advisory (MISC) http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html - Exploit, Third Party Advisory, VDB Entry
Information

Published : 2021-03-03 00:15

Updated : 2025-10-30 19:55

NVD link : CVE-2021-26855

Mitre link : CVE-2021-26855

CVE.ORG link : CVE-2021-26855

JSON object : View

Products Affected

microsoft

  • exchange_server
CWE
CWE-918

Server-Side Request Forgery (SSRF)