SummaryAI-written · claude-haiku-5-5AI-written · claude-haiku-5-5Written by a language model from the source data on this page. Not reviewed by a person. Generated 23 Oct 2026.
The flaw is an elevation of privilege vulnerability in Microsoft Active Directory Domain Services, a component of Active Directory, stemming from improper input validation. An attacker holding low-privilege credentials on the network can exploit it without any user interaction, with success depending on a high-complexity attack condition, to gain elevated privileges.
Official description · NVDSource dataSource dataCopied from an authoritative feed: NVD, CVE.org, CISA KEV, FIRST EPSS or MITRE CTID mappings, or labelled by the annotators of a published dataset. Copied from NVD.
Active Directory Domain Services Elevation of Privilege Vulnerability
Priority scorePatchfirst’s 0 to 100 ranking. It adds points for CISA KEV listing, ransomware use, EPSS, threat reports, public exploit code and CVSS. Every CVE page shows the breakdown.Breakdown
82.0 / 100
Exploited
Yes, in CISA KEV
Reports
1
Tactics
4/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 5 months after disclosure. Public exploit code (PoC-in-GitHub) appeared 31 days after disclosure.
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order, 2 cited passagesAIAI-writtenWritten by a language model from the source data on this page. Not reviewed by a person.2
Initial AccessTA0001
Valid AccountsT1078Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.also Persistence, Privilege Escalation, Stealth
AI-written · claude-haiku-5-5AI-written · claude-haiku-5-5Written by a language model from the source data on this page. Not reviewed by a person. claude-haiku-5-5: Escalated privileges enable use of valid accounts.AI mapping from the description · primary impact
Escalated privileges enable use of valid accounts
Active Directory Domain Services Elevation of Privilege Vulnerability
Exploitation for Privilege EscalationT1068Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
AI-written · claude-haiku-5-5AI-written · claude-haiku-5-5Written by a language model from the source data on this page. Not reviewed by a person. claude-haiku-5-5: Vulnerability itself is privilege escalation via exploitation.AI mapping from the description · how it is exploited
Vulnerability itself is privilege escalation via exploitation
Active Directory Domain Services Elevation of Privilege Vulnerability
2 rules for this CVE · 87 general rules for its techniques
Rules for this CVE
2Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2021-42278 directly.
Named in 1 threat reportMachineMachine-matchedFound by keyword or pattern matching over threat-report text. Not reviewed by a person. Exact CVE id found in the report text.
1 reportGroup-IB
Reports are matched by finding the exact id CVE-2021-42278 in their text; nobody has reviewed the match. One passage is shown per report, at most 320 characters, linked to the original.
The vulnerability labelled as CVE-2021-42278 enables an attacker with limited domain user credentials to obtain a Kerberos service ticket for the domain controller, ultimately allowing them to compromise the domain controller.