Threats / Microsoft / CVE-2025-21333
CVE-2025-21333
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Microsoft Windows vulnerability
A heap-based buffer overflow in Windows Hyper-V NT Kernel Integration VSP allows local attackers to escalate privileges to SYSTEM level.
Verdict
Today item — known-exploited.
This vulnerability enables privilege escalation from local access to SYSTEM rights through memory corruption. Active exploitation in the wild increases risk. Affected systems require immediate patching.
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
7 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 0.09798 — 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-122 Heap-based Buffer Overflow — 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 or compromised user account exists on the network.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger the heap-based buffer overflow in the Hyper-V VSP component through a crafted input or operation.
Business
The vulnerability is reachable without additional exploits or user interaction.
3
Lateral reach — past segmentation narrative 3
Attacker
I corrupt heap memory to overwrite control structures and redirect execution to my payload.
Business
Memory safety failures in kernel-level code create direct privilege escalation paths.
4
Data at risk — exfiltration narrative 4
Attacker
I achieve code execution with SYSTEM privileges on the host or guest VM.
Business
Attackers gain full control of critical infrastructure and can move laterally across the environment.
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