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CVE-2021-26857: Microsoft Exchange Server

EPSS95.7%No. 349 of 1739 in KEV
CVE year2021listed the same year
Same vendor in KEV389
Same product17
FieldValue
VendorMicrosoft
ProductExchange Server
NameMicrosoft Exchange Server Remote Code Execution Vulnerability
Added to KEV2021-11-03
US federal due date2022-05-03
Ransomware useKnown
CWECWE-502

CISA description

Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.

Other entries for this product

CVEVendor / productAddedEPSSRansomware
CVE-2023-21529Microsoft Exchange Server2026-04-1359.2%Known
CVE-2021-31196Microsoft Exchange Server2024-08-2154.0%Unknown
CVE-2024-21410Microsoft Exchange Server2024-02-1512.5%Unknown
CVE-2022-41080Microsoft Exchange Server2023-01-1077.3%Known
CVE-2022-41082Microsoft Exchange Server2022-09-3099.9%Known
CVE-2022-41040Microsoft Exchange Server2022-09-3099.9%Known
CVE-2018-8581Microsoft Exchange Server2022-03-0327.3%Known
CVE-2021-33766Microsoft Exchange Server2022-01-1898.1%Unknown
CVE-2021-34523Microsoft Exchange Server2021-11-0399.9%Known
CVE-2021-34473Microsoft Exchange Server2021-11-0399.9%Known
CVE-2021-31207Microsoft Exchange Server2021-11-0399.7%Known
CVE-2021-27065Microsoft Exchange Server2021-11-0399.8%Known
CVE-2021-26858Microsoft Exchange Server2021-11-0393.6%Known
CVE-2021-26855Microsoft Exchange Server2021-11-0399.9%Known
CVE-2020-17144Microsoft Exchange Server2021-11-0336.5%Unknown

NVD — CVE-2021-26857

Data from CISA's Known Exploited Vulnerabilities (KEV) catalog. EPSS is FIRST's estimated probability of exploitation activity in the next 30 days, refreshed weekly. Always follow the vendor's official guidance.
About this page

A Microsoft Exchange Server vulnerability added to CISA's Known Exploited Vulnerabilities catalog on 2021-11-03.