Overview
Microsoft HTTP Protocol Stack contains a vulnerability in http.sys that allows for remote code execution.
https://nvd.nist.gov/vuln/detail/CVE-2021-31166
Key Details
| Property | Value |
|---|---|
| CVE ID | CVE-2021-31166 |
| Vendor / Product | Microsoft — HTTP Protocol Stack |
| NVD Published | 2021-05-11 |
| NVD Last Modified | 2025-10-30 |
| CVSS 3.1 Score | 9.8 |
| CVSS 3.1 Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Severity | CRITICAL |
| CWE | CWE-416 |
| CISA KEV Added | 2022-04-06 |
| CISA KEV Deadline | 2022-04-27 |
| Known Ransomware Use | No |
CVSS 3.1 Breakdown
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Required Action
CISA BOD 22-01 Deadline: 2022-04-27.
Apply updates per vendor instructions.
Timeline
| Date | Event |
|---|---|
| 2022-04-06 | Added to CISA Known Exploited Vulnerabilities catalog |
| 2022-04-27 | CISA BOD 22-01 remediation deadline |
References
| Resource | Type |
|---|---|
| NVD — CVE-2021-31166 | Vulnerability Database |
| CISA KEV Catalog Entry | US Government |