Microsoft Malware Protection Engine Defender code injection

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
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.
7.5$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Microsoft Malware Protection Engine. The affected element is an unknown function of the component Defender. Executing a manipulation can lead to an unknown weakness. This vulnerability is tracked as CVE-2021-42298. The attack can be launched remotely. No exploit exists. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability has been found in Microsoft Malware Protection Engine (Anti-Malware Software) (affected version not known) and classified as critical. This vulnerability affects some unknown functionality of the component Defender. The CWE definition for the vulnerability is CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. As an impact it is known to affect confidentiality, integrity, and availability.

The weakness was disclosed 11/09/2021 as confirmed security guidance (Website). The advisory is shared for download at portal.msrc.microsoft.com. This vulnerability was named CVE-2021-42298. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/21/2026). The MITRE ATT&CK project declares the attack technique as T1059.

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

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.1
VulDB Meta Temp Score: 7.5

VulDB Base Score: 8.8
VulDB Temp Score: 7.7
VulDB Vector: 🔍
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 7.8
Vendor Vector (Microsoft): 🔍

NVD Base Score: 7.8
NVD Vector: 🔍

CNA Base Score: 7.8
CNA Vector (Microsoft): 🔍

CVSSv2info

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

NVD Base Score: 🔍

Exploitinginfo

Class: Code injection
CWE: CWE-94 / CWE-74 / CWE-707
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: Yes

Availability: 🔍
Status: Unproven

EPSS Score: 🔍
EPSS Percentile: 🔍

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: 🔍

Timelineinfo

10/12/2021 🔍
11/09/2021 +28 days 🔍
11/09/2021 +0 days 🔍
11/10/2021 +0 days 🔍
08/21/2026 +1745 days 🔍

Sourcesinfo

Vendor: microsoft.com

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

CVE: CVE-2021-42298 (🔍)
GCVE (CVE): GCVE-0-2021-42298
GCVE (VulDB): GCVE-100-186412

Entryinfo

Created: 11/10/2021 08:41
Updated: 08/21/2026 09:40
Changes: 11/10/2021 08:41 (33), 11/10/2021 08:45 (21), 11/12/2021 07:49 (2), 08/21/2026 09:40 (44)
Complete: 🔍
Cache ID: 216::103

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