Threats / Microsoft / CVE-2020-1040
CVE-2020-1040
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Microsoft Hyper-V RemoteFX vulnerability
Microsoft Hyper-V RemoteFX vGPU fails to validate input from authenticated guest users, enabling remote code execution on the host operating system.
Verdict
Today item — known-exploited.
An authenticated attacker with guest OS access can exploit improper input validation in RemoteFX vGPU to execute arbitrary code on the Hyper-V host, compromising the entire virtualization infrastructure and all hosted guests.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
3 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 2021-11-03).
Probability (EPSS)
EPSS 0.06903 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Microsoft, Hyper-V RemoteFX. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-20 Improper Input Validation.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 authenticate to a guest virtual machine and send specially crafted input to the RemoteFX vGPU interface.
Business
Guest isolation is bypassed, exposing the hypervisor to direct attack from tenant workloads.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I exploit the input validation flaw to execute arbitrary code with host-level privileges.
Business
The Hyper-V host is compromised, enabling lateral movement to all virtual machines and underlying infrastructure.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistent control over the virtualization platform and its hosted environment.
Business
Multi-tenant environments face complete infrastructure compromise, data exfiltration, and service disruption across all hosted systems.
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