Microsoft Windows 10 20H2/10 2004/Server 20H2/Server 2004 HTTP Protocol Stack use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
9.4$0-$5k0.00

Summaryinfo

A vulnerability was found in Microsoft Windows 10 20H2/10 2004/Server 20H2/Server 2004. It has been classified as very critical. This impacts an unknown function of the component HTTP Protocol Stack. This manipulation causes an unknown weakness. This vulnerability is registered as CVE-2021-31166. Remote exploitation of the attack is possible. Furthermore, an exploit is available. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability has been found in Microsoft Windows 10 20H2/10 2004/Server 20H2/Server 2004 (Operating System) and classified as very critical. Affected by this vulnerability is an unknown code block of the component HTTP Protocol Stack. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability.

The weakness was published 05/11/2021 as confirmed security guidance (Website). The advisory is shared at portal.msrc.microsoft.com. This vulnerability is known as CVE-2021-31166. Technical details are unknown but a public exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/08/2025).

A public exploit has been developed by Axel Souchet (0vercl0k) in Python and been published 5 days after the advisory. It is possible to download the exploit at github.com. It is declared as attacked. We expect the 0-day to have been worth approximately $100k and more. The CISA Known Exploited Vulnerabilities Catalog lists this issue since 04/06/2022 with a due date of 04/27/2022:

Apply updates per vendor instructions.

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.8
VulDB Meta Temp Score: 9.4

VulDB Base Score: 9.8
VulDB Temp Score: 9.4
VulDB Vector: 🔍
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 9.8
Vendor Vector (Microsoft): 🔍

NVD Base Score: 9.8
NVD Vector: 🔍

CNA Base Score: 9.8
CNA Vector (Microsoft): 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Access: Public
Status: Attacked
Author: Axel Souchet (0vercl0k)
Programming Language: 🔍
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

KEV Added: 🔍
KEV Due: 🔍
KEV Remediation: 🔍
KEV Ransomware: 🔍
KEV Notice: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍
Exploit Delay Time: 🔍

Timelineinfo

04/14/2021 🔍
05/11/2021 +27 days 🔍
05/11/2021 +0 days 🔍
05/12/2021 +0 days 🔍
05/16/2021 +3 days 🔍
02/08/2025 +1364 days 🔍

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: portal.msrc.microsoft.com
Status: Confirmed

CVE: CVE-2021-31166 (🔍)
GCVE (CVE): GCVE-0-2021-31166
GCVE (VulDB): GCVE-100-174865
scip Labs: https://www.scip.ch/en/?labs.20161215

Entryinfo

Created: 05/12/2021 07:06
Updated: 02/08/2025 00:25
Changes: 05/12/2021 07:06 (8), 05/12/2021 07:07 (26), 05/12/2021 07:10 (21), 05/13/2021 14:51 (2), 05/16/2021 20:44 (4), 05/16/2021 20:45 (4), 04/25/2024 14:43 (28), 07/10/2024 00:34 (27), 09/21/2024 10:49 (1), 02/08/2025 00:25 (1)
Complete: 🔍
Committer: misc
Cache ID: 216:730:103

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