CVE-2021-42298: microsoft malware_protection_engine Code Injection
CVSS: 9.3v2.0HighModified
Published 10-11-2021Last modified 19-08-2026
Vulnerability summary
CVE-2021-42298 is a high (CVSS 9.3) Code Injection vulnerability in microsoft malware_protection_engine. EPSS estimates a 5.85% chance of exploitation in the next 30 days, higher than 93.1% of scored vulnerabilities.
CVSS score
9.3/10
010
High · v2.0 (NVD)EPSS score
5.85%
0%100%
Low · +0.05 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 10-11-2021PublishedVulnerability first disclosed.
- 19-08-2026Last modifiedVulnerability information updated.
Description
Microsoft Defender Remote Code Execution Vulnerability
CVSS metrics
3 scores · 2 sources · 2 versionsHigh 7.8Preferred score · CVE.org (CNA)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:CSourcesAll 2 agree
- NVDNIST7.8HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
High 9.3Preferred score · NVD (NIST)
AV:N/AC:M/Au:N/C:C/I:C/A:CSourcesSingle source
EPSS trend
Probability
5.85%
Chance of exploitation in the next 30 days
Percentile
93%
Versus all other CVEs
30-day change
+0.05 pp
From 5.80% on 19-09-2026
19-09-202619-10-2026
EPSS score5.85%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Microsoft2 products
- malware_protection_engine< 1.1.18700.3
- microsoft malware protection engine≥ 1.1.0.0, < 1.1.18700.3
1 vendor · 2 products
References
2 links
- portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42298X Refsource MISCX TransferredMitigationPatchVendor Advisory