Threats / Microsoft / CVE-2021-34484
CVE-2021-34484
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Microsoft Windows vulnerability
Microsoft Windows User Profile Service privilege escalation vulnerability (CWE-269) allowing attackers to gain elevated system access. Actively exploited in the wild.
Verdict
Today item — known-exploited.
A privilege escalation flaw in Windows User Profile Service enables local attackers to escalate from limited to elevated privileges. Active exploitation demonstrates practical attack viability and poses significant risk to Windows deployments.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
4 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 2022-03-31).
Probability (EPSS)
EPSS 0.14393 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Microsoft, Windows. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-269 Improper Privilege Management — weakness family: Authorization / access control.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
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
I gain initial access to a Windows system with limited user privileges through phishing, credential compromise, or supply chain infection.
Business
Attackers establish a foothold on enterprise endpoints, bypassing initial access controls and creating persistence opportunities.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I exploit the User Profile Service vulnerability to escalate my privileges from standard user to SYSTEM or administrator level.
Business
Elevated privileges enable attackers to install malware, modify system configurations, access sensitive data, and move laterally across the network.
3
Lateral reach — past segmentation narrative 3
Attacker
I maintain persistent control over the compromised system and pivot to other network resources using administrative credentials.
Business
Widespread system compromise leads to data exfiltration, operational disruption, and potential regulatory violations across the organization.
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