CVE-2021-1647
Microsoft Defender Remote Code Execution Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 November 2021). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
Microsoft Defender Remote Code Execution Vulnerability
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 39.65% probability · 99th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 3 November 2021 · due 17 November 2021
- Affected
- microsoft/windows defender · microsoft/security essentials · microsoft/system center endpoint protection
- Source
- secure@microsoft.com
EPSS 39.7% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-1647
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1647Patch, Vendor Advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1647Patch, Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1647US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.