Domain-controller impersonation via missing PAC requestor validation
Published Nov 10, 2021 · Updated Aug 19, 2026
Improper privilege management in Active Directory Domain Services allows remote authenticated users to impersonate domain controllers. The Kerberos KDC issues a higher-privilege service ticket without binding the named account to the original TGT requestor recorded in the PAC. Exploitation requires a compromised domain account and yields domain-controller identity, enabling domain-wide privileged access.
Summary
What happened
Improper privilege management in Active Directory Domain Services allows remote authenticated users to impersonate domain controllers. The Kerberos KDC issues a higher-privilege service ticket without binding the named account to the original TGT requestor recorded in the PAC. Exploitation requires a compromised domain account and yields domain-controller identity, enabling domain-wide privileged access.
The record
- CVE
- CVE-2021-42287
- Published
- Nov 10, 2021
- Updated
- Aug 19, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- CWE-269, T1558
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 10, 2021CVE publishedPublication date reported by the CVE source.
- Apr 11, 2022Exploitation reportedCISA Known Exploited Vulnerabilities catalog listing
- Aug 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.17763.0 <10.0.17763.2300
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- noPacfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- CISA Known Exploited Vulnerabilities catalog listingknown exploited catalog
- CISA-recorded ransomware campaign useransomware
Technologies
Your stack
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Your stack
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