CVE-2026-56188

Windows Server Network driver Remote Code Execution Vulnerability

No known exploitation. EPSS puts it in the 47th percentile. A vendor fix is available.

CVSS 3.19.8Critical EPSS percentile47th0.6% chance in 30 days CISA KEVNot listedNo confirmed exploitation
No public exploit known FixVendor fixNo build named by the sources

Published 2026-07-14Updated 2026-07-22Sources: CVE.org, NVD

NVD CVE.org

What to do

The vendor has published a fix. Version details are below where the sources state them.

Steps

Written by AI from the record

Check your Windows version and whether it is one of: windows 10, windows 11, windows server 2012, windows server 2012 r2, windows server 2016, windows server 2019, windows server 2022, windows server 2025.
Compare your installed build/revision against the fixed versions below, and treat any earlier-than-fixed systems as vulnerable.
Update Windows to the fixed version for your edition:
- windows 10 → 10.0.14393.9339 or 10.0.17763.9020 or 10.0.19044.7548 or 10.0.19045.7548
- windows 11 → 10.0.26100.8875 or 10.0.28000.2525
- windows server 2012 → 6.2.9200.26226
- windows server 2012 r2 → 6.3.9600.23291
- windows server 2016 → 10.0.14393.9339
- windows server 2019 → 10.0.17763.9020
- windows server 2022 → 10.0.20348.5386
- windows server 2025 → 10.0.26100.33158
If you cannot patch immediately, reduce exposure by restricting inbound network access to Windows hosts (allow only the necessary management and business services) until updates are applied.

Usually a quick update

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Server Network driver allows an unauthorized attacker to execute code over a network.

In plain language

Written by AI from the record

This is a critical Windows remote-code flaw where an attacker can run malicious code over the network on unpatched systems, so most small businesses using these Windows versions should act quickly.

CVE-2026-56188 is a race-condition Remote Code Execution issue in the Windows Server Network driver that can be triggered remotely without authentication or user interaction, allowing arbitrary code execution over the network on vulnerable systems.

If you're affected

Full system takeover
Ransomware risk
File and data theft
Business downtime

What is it

Think of the Windows network component like a door worker that handles many requests at the same time. This issue is a timing problem (a “race condition”) that can let an attacker use the network to make that component do unintended actions—up to running attacker code on the server.

Analogy: it’s like two people both trying to open the same door lock at once, and the lock ends up in a state where someone who shouldn’t have access can get in.

Who is affected

This matters if you run or manage any of these systems: windows 10, windows 11, windows server 2012, windows server 2012 r2, windows server 2016, windows server 2019, windows server 2022, windows server 2025.

It’s reachable over the network and does not require login or user actions, so any reachable Windows host could be targeted—only a risk if it is exposed to untrusted network traffic (for example, reachable from the internet or from other untrusted networks).

How urgent is it

This is RED because it is a remote code execution weakness with no authentication and no user interaction required. Attackers can potentially target vulnerable Windows systems directly over the network.

Even though there is no confirmed KEV entry and no dated exploitation report in the provided findings, the combination of remote reachability and code-execution impact makes it urgent to patch.

What to do — in detail

Confirm exposure scope
- Identify every machine running one of the affected products: windows 10, windows 11, windows server 2012, windows server 2012 r2, windows server 2016, windows server 2019, windows server 2022, windows server 2025.
- For each host, determine where it is reachable from: internet-facing IPs, VPN segments, office-to-cloud peering, and any flat internal networks with other organizations.
Check current build against fixed versions
- On each Windows host, record the OS build number/revision (the exact “version/build” your system reports).
- Treat the host as vulnerable if it is earlier than the fixed version for its specific Windows release branch.
Patch/upgrade to the fixed builds
- windows 10:
  - fixed in 10.0.14393.9339 OR 10.0.17763.9020 OR 10.0.19044.7548 OR 10.0.19045.7548
- windows 11:
  - fixed in 10.0.26100.8875 OR 10.0.28000.2525
- windows server 2012:
  - fixed in 6.2.9200.26226
- windows server 2012 r2:
  - fixed in 6.3.9600.23291
- windows server 2016:
  - fixed in 10.0.14393.9339
- windows server 2019:
  - fixed in 10.0.17763.9020
- windows server 2022:
  - fixed in 10.0.20348.5386
- windows server 2025:
  - fixed in 10.0.26100.33158
Rollout plan (practical order)
- Patch servers first (especially those that handle remote access, file sharing, or are commonly reachable).
- Patch remaining endpoints after server-side risks are reduced.
- Validate after reboot/update by re-checking the reported build number.
Temporary workaround if patching is delayed
- Restrict inbound network traffic to only what is required for your business.
- Block unsolicited inbound connections to Windows hosts from untrusted networks.
- If you use remote administration, ensure it is limited to trusted IPs/VPN rather than open exposure.
What to monitor after updating
- Confirm no unexpected new remote connections are occurring.
- Review security logs for signs of unusual service activity or crashes in network-related components.
KEV / due date
- This CVE is not listed in the CISA KEV feed in the provided findings, so no KEV-driven due date is known from the supplied data.

Technical context

Severity: Critical (CVSS 9.8). The weakness is CWE-362 (race condition). The reported mechanism is a race condition involving shared resources in the Windows Server Network driver that can result in unauthorized remote attackers executing arbitrary code.

Attack vector and trigger: remote network-based triggering with no authentication and no user interaction required, meaning an attacker can attempt exploitation purely by reaching the vulnerable surface.

Exploitation status from findings: KEV is not listed and no clear dated press exploitation claim is provided; no public exploit code is recorded. Patch availability is confirmed with fixed versions across multiple Windows 10/11 and Windows Server releases.

EPSS/other metrics: not provided in the supplied findings; exploitation maturity beyond patch availability is not established here.

This is a general assessment based on public vulnerability data. It does not account for your specific infrastructure — when in doubt, consult a security specialist.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS47th

CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

0.6% chance of exploitation activity in the next 30 days, which ranks it in the 47th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

11 events over 8 days, from the signal feeds we watch.

2026-07-22Patch availablepatch available, record updated, record updated
2026-07-17Analysis publishedMicrosoft's biggest Patch Tuesday ever: what I'd actually fix first
2026-07-16OpenVAS check added
2026-07-14Publishedweakness classified, att&ck mapped, record updated, record updated

Affected products

Microsoftcommercial · US

And 22 more affected products. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 9.8 by NVD.

How it is reached

Attack Vector NetworkExploitable remotely over the network without any special conditions
Attack Complexity LowNo special conditions — the attack can be reliably reproduced
Privileges Required NoneNo authentication required — anyone can exploit this
User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

Confidentiality HighTotal information disclosure — all data in the component is compromised
Integrity HighTotal loss of integrity — attacker can modify any data in the component
Availability HighTotal denial of service — the component is completely unavailable