CVE-2021-26858

HIGH severity · CVSS 7.8 · actively exploited (CISA KEV)

7.8CVSS HIGH ● exploited ⚠ ransomware

🔴 Actively exploited in the wild (CISA Known Exploited Vulnerabilities). ⚠ Known use in ransomware campaigns. Added to KEV 2021-11-03. US federal agencies must patch by 2022-05-03.

Summary

Microsoft Exchange Server Remote Code Execution Vulnerability

Impact & exploitability

Attack vectorLocal

Attack complexityLow

Privileges requiredNone

User interactionRequired

Confidentiality impactHigh

Integrity impactHigh

Availability impactHigh

Exploit probability (EPSS)73%

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products we track (1)

Microsoft Exchange Server

Recommendation

This vulnerability is being actively exploited in the wild — patch affected products urgently. Open any affected product above for its exact safe version.

Official patch: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26858 ↗

Additional information

NVD record
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26858Patch
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26858Patch
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26858