VulnerabilityAnalyzed
CVE-2021-26858
Microsoft Exchange Server Remote Code Execution Vulnerability
KEVHIGH 7.8EPSS 93.7%
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 3 May 2022). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
Microsoft Exchange Server Remote Code Execution Vulnerability
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- EPSS
- 93.65% probability · 100th percentile
- CISA KEV
- Listed 3 November 2021 · due 3 May 2022 · used in ransomware campaigns
- Affected
- microsoft/exchange server
- Source
- secure@microsoft.com
CISA notes
Apply updates per vendor instructions. Reference CISA's ED 21-02 (https://www.cisa.gov/news-events/directives/ed-21-02-mitigate-microsoft-exchange-premises-product-vulnerabilities) for further guidance and requirements. Note: The due date for addressing this vulnerability aligns with the requirements outlined in ED 21-02. https://nvd.nist.gov/vuln/detail/CVE-2021-26858
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26858Patch, Vendor Advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26858Patch, Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26858US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.