Microsoft · Defender
CVE-2021-1647
Microsoft Defender Remote Code Execution Vulnerability
CISA KEV record
- CISA date added
- 2021-11-03
- CISA due date
- 2021-11-17
- Known ransomware use
- Unknown
NVD risk context
7.8 HIGH
CVSS is a technical severity score. CISA’s KEV status remains the evidence that this vulnerability is known to be exploited.
Description
Microsoft Defender contains an unspecified vulnerability that allows for remote code execution.
Required action
Apply updates per vendor instructions.
NVD reference index
Vendor and remediation references
NVD has tagged these sources as vendor advisories, patches, mitigations, or release notes.
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1647 ↗
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1647 ↗
Other NVD references (1)
MITRE CWE context
CWE classification
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
View official MITRE CWE details ↗The product receives input that is expected to specify an index, position, or offset into an indexable resource such as a buffer or file, but it does not validate or incorrectly validates that the specified index/position/offset has the required properties.
View official MITRE CWE details ↗NVD record timing
NVD record timeline
These dates describe NVD’s record, not CISA’s KEV addition or remediation due date.
- NVD published
- Jan 12, 2021, 08:15 PM UTC When NVD first published this CVE record.
- NVD last updated
- Jun 17, 2026, 03:32 AM UTC When NVD last changed its analysis or record data.
Advanced: view the technical CVSS vector
This standardized code is intended for security tools and technical analysts. The plain-language risk summary above explains its main points.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA notes
https://nvd.nist.gov/vuln/detail/CVE-2021-1647