SARA / Free Tools / KEV / CVE-2021-26857

CVE-2021-26857 on CISA KEV

Microsoft Exchange Server Remote Code Execution Vulnerability

CISA KEV — Actively Exploited

Microsoft Exchange Server Remote Code Execution Vulnerability

Vendor / Product
— / Microsoft / Exchange Server
Added to KEV
2021-11-03
BOD 22-01 due
2022-05-03
Ransomware use
Known
CVSS / EPSS
7.8 HIGH · EPSS 40.47%

01What CISA says about this vulnerability

Microsoft Exchange Server Remote Code Execution Vulnerability

02Required action — verbatim from CISA

Apply updates per vendor instructions.

03Notes & references

04SARA's analyst layer — why this matters

This vulnerability is currently on the CISA KEV list, which CISA only adds CVEs to when there is reliable evidence of active exploitation in the wild. For federal civilian agencies, BOD 22-01 requires remediation by the due date above. For everyone else, KEV is the strongest "patch immediately" signal you can get from public threat intel.

05Affected products (summary)

VendorProductVersions
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1915.01.0
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 815.02.0
MicrosoftMicrosoft Exchange Server 201915.02.0
MicrosoftMicrosoft Exchange Server 2013 Cumulative Update 2215.00.0
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 215.02.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1315.01.0
MicrosoftMicrosoft Exchange Server 2013 Cumulative Update 2315.00.0
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 315.02.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1415.01.0
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 415.02.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1515.01.0
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 515.02.0
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 615.02.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1615.01.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1715.01.0
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 715.02.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1815.01.0
MicrosoftMicrosoft Exchange Server 2010 Service Pack 314.0.0.0
MicrosoftMicrosoft Exchange Server 2013 Service Pack 115.00.0
MicrosoftMicrosoft Exchange Server 2013 Cumulative Update 2115.00.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1215.01.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 815.01.0
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 115.02.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 915.01.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1015.01.0
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 1115.01.0

06Detection

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection:

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