Threats / Microsoft / CVE-2021-42287
CVE-2021-42287
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Active Directory vulnerability
Microsoft Active Directory Domain Services privilege escalation vulnerability enabling unauthorized elevation of account permissions within directory infrastructure.
Verdict
Today item, not a backlog item.
Active Directory privilege escalation flaw with high exploitation likelihood. Attackers gain elevated permissions to compromise domain resources, user accounts, and organizational security controls. Widely exploited in ransomware campaigns.
CISA KEV Yes · 2022-04-115Ransomware use Flagged5EPSS 0.74265 (verify live)6Exploit Public PoC7CVSS 7.53CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
15 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-04-11), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.74265 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.5 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C) · Affected: Microsoft, Active Directory. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-269 Improper Privilege Management — weakness family: Authorization / access control.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 152 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
Obtain valid domain user credentials through phishing or credential compromise.
Business
Initial foothold established within authenticated directory environment.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
Exploit privilege escalation flaw to elevate from standard user to administrative or domain admin level.
Business
Attacker gains control over critical identity and access management systems.
3
Lateral reach — past segmentation narrative 3
Attacker
Leverage elevated permissions to move laterally across domain-joined systems and access sensitive data.
Business
Organizational infrastructure becomes compromised; data exfiltration and lateral movement enabled.
4
Data at risk — exfiltration narrative 4
Attacker
Deploy ransomware payloads across compromised domain infrastructure with administrative privileges.
Business
Enterprise-wide encryption and operational shutdown; significant financial and reputational damage.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05