Threats / Microsoft / CVE-2025-21335
CVE-2025-21335
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Microsoft Windows vulnerability
A use-after-free vulnerability in 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 Hyper-V kernel component. Exploitation requires local access but yields highest system privilege, enabling full system compromise.
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 0.01363 — 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 gain initial local access to a Windows system running Hyper-V.
Business
An insider, contractor, or compromised user account exists on the network.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger the use-after-free condition in the Hyper-V NT Kernel Integration VSP component through crafted local operations.
Business
The vulnerability is reachable without special configuration or additional exploits.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary code with SYSTEM privileges by exploiting the freed memory reference.
Business
The attacker gains unrestricted control over the entire host system and all hosted virtual machines.
4
Data at risk — exfiltration narrative 4
Attacker
I persist access, disable security controls, and move laterally across the infrastructure.
Business
Containment fails; the compromise spreads to dependent systems, data stores, and connected networks.
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