CVE-2020-1040

A remote code execution vulnerability exists when Hyper-V RemoteFX vGPU on a host server fails to properly validate input from an authenticated user on a guest operating system, aka 'Hyper-V RemoteFX vGPU Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2020-1032, CVE-2020-1036, CVE-2020-1041, CVE-2020-1042, CVE-2020-1043.

CVSS: 9.0Criticalscored by CISA
Exploited in the wild: Yes, in CISA KEV since 3 Nov 2021CISA deadline for US federal agencies: 3 May 2022
EPSS: 7.6%chance of exploitation in the next 30 daystop 6% of scored CVEsFIRST score of 11 Nov 2026
Fix: Patch availablesee the advisories in the references
Published: 14 Jul 2020analysed here 12 Nov 2026

Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)

Summary

Triage

Exploitable: At runtime
Attack vector: adjacent network
Weakness: CWE-20 Improper Input Validation
Can a WAF block it?: No. See why

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Product	Affected versions	Vendor says fixed in
Microsoft Windows Server	20162016 (Core installation)2008 R2 for x64-based Systems Service Pack 12008 R2 for x64-based Systems Service Pack 1 (Core installation)20122012 (Core installation)2012 R22012 R2 (Core installation)Vendor says fixed in: not stated	Not stated by the vendor

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

Products named in our analysis

microsoft:windows_server_2008
microsoft:windows_server_2012
microsoft:windows_server_2016

Fix and mitigation

WAF and other mitigations

Can a WAF block it? No. The attack does not come over the network, so a WAF is not on its path. Patching is the reliable fix.

Also consider: patch

Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Listed since 3 Nov 2021.
CISA due date: 3 May 2022, the remediation deadline for US federal agencies
CISA required action: Apply updates per vendor instructions.
Public exploit code: None on record in Exploit-DB, Metasploit, Nuclei templates or PoC-in-GitHub.
CISA SSVC: exploitation active, automatable no, technical impact totalAssessed by CISA 4 Feb 2025 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.

Timeline

14 Jul 2020Published
3 Nov 2021Added to CISA KEV (exploited in the wild)476 days (about 1 year) later
3 May 2022CISA remediation due date (US federal agencies)181 days (about 6 months) later
4 Feb 2025CISA SSVC assessment: exploitation active1,009 days (about 3 years) later
21 Oct 2025CVE record last updated259 days (about 9 months) later
12 Nov 2026Analysed by vulneraibility.com387 days (about 1 year) later

CVSS vector

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Metric	Value	What it means
Attack vector	AdjacentSame subnet or link layer.	Same subnet or link layer.
Attack complexity	LowRepeatable attack, no special conditions.	Repeatable attack, no special conditions.
Privileges required	LowThe attacker needs basic user privileges.	The attacker needs basic user privileges.
User interaction	NoneNo victim action needed.	No victim action needed.
Scope	ChangedImpact crosses a security boundary into other components.	Impact crosses a security boundary into other components.
Confidentiality	HighTotal data disclosure possible.	Total data disclosure possible.
Integrity	HighComplete modification possible.	Complete modification possible.
Availability	HighFull outage possible.	Full outage possible.

Common questions

Is CVE-2020-1040 being exploited?

Yes. CVE-2020-1040 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.

How severe is CVE-2020-1040?

CVE-2020-1040 is rated Critical with a CVSS score of 9.0. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2020-1040?

Yes. A fix has been recorded for CVE-2020-1040. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2020-1040 affect?

CVE-2020-1040 affects microsoft:windows_server_2008, microsoft:windows_server_2012, microsoft:windows_server_2016. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

3 references in the CVE record, grouped by the tags the record gives them.

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
CISA KEV catalog: exploitation, date added, due date
CISA Vulnrichment (ADP): SSVC decision points
FIRST EPSS: exploit probability and percentile

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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