7.5

CVE-2021-42278: Microsoft Active Directory Domain Services Privilege Escalation Vulnerability

CVSS: 7.5v3.1HighKEVRansomwareAnalyzed
Published 10-11-2021Last modified 19-08-2026
Open JSON

Vulnerability summary

CVE-2021-42278 is a high (CVSS 7.5) vulnerability in Microsoft Active Directory. It is known to be exploited: CISA lists it, first on 11-04-2022. It has been used in ransomware campaigns. EPSS estimates a 73.30% chance of exploitation in the next 30 days, higher than 99.4% of scored vulnerabilities.

Overall risk
90/100
0100
Critical · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
73.30%
0%100%
Critical · 0.00 pp in 30 days
KEVListedCISA
RansomwareKnown useFlagged by CISA
Public exploits0No public exploits recorded

Timeline

  1. 10-11-2021
    PublishedVulnerability first disclosed.
  2. 11-04-2022
    Added to CISA KEVMicrosoft Active Directory Domain Services Privilege Escalation Vulnerability
  3. 02-05-2022
    CISA remediation dueApply updates per vendor instructions.
  4. 19-08-2026
    Last modifiedVulnerability information updated.

Description

Active Directory Domain Services Elevation of Privilege Vulnerability

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

73.30%

Chance of exploitation in the next 30 days

Percentile

99%

Versus all other CVEs

30-day change

0.00 pp

From 73.30% on 19-09-2026

19-09-202619-10-2026
EPSS score
73.30%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
11-04-2022
Federal due date
02-05-2022
Ransomware

CISA required action

Apply updates per vendor instructions. nvd.nist.gov/vuln/detail/CVE-2021-42278

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Microsoft18 products

1 vendor · 18 products

References

3 links