Threats / Microsoft / CVE-2025-21334
CVE-2025-21334
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Microsoft Windows vulnerability
A use-after-free vulnerability in Microsoft Windows Hyper-V NT Kernel Integration VSP allows local attackers to escalate privileges to SYSTEM level.
Verdict
Today item — known-exploited.
Local privilege escalation via memory safety defect in kernel-mode Hyper-V component. Exploitation requires local code execution context but yields highest system privilege. Active exploitation observed in wild.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
6 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 2025-01-14).
Probability (EPSS)
EPSS 0.0153 — 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-416 Use After Free — weakness family: Memory safety.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 execute code with user-level privileges on a Windows system running Hyper-V.
Business
Attacker gains foothold through prior compromise or insider access.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger the use-after-free condition in the Hyper-V VSP kernel driver by manipulating memory references.
Business
Vulnerability in kernel component creates exploitable state.
3
Lateral reach — past segmentation narrative 3
Attacker
I achieve arbitrary code execution in kernel context and escalate to SYSTEM privileges.
Business
Complete system compromise; attacker gains unrestricted control over host.
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