Windows 10 21h2Operating system · Microsoft

CVE-2025-26639

HIGH · 7.8 CVSS v3.1 Published 2025-04-08

Fix available

A fix is available. Upgrade to 10.0.19044.5737 / 10.0.19045.5737 or later.

See remediation →

80/100

Remediation priority · High

Zero-click

Official description

NVD · unedited

Integer overflow or wraparound in Windows USB Print Driver allows an authorized attacker to elevate privileges locally.

Technical summary

dbcve analysis · high confidence

Integer overflow vulnerability in Windows USB Print Driver allows a local authenticated attacker to execute code with elevated privileges. The flaw exists in how the driver handles certain USB printer communications, where improper integer arithmetic leads to memory corruption that can be leveraged for privilege escalation.

MitigationApply the Microsoft security update for CVE-2025-26639 through standard Windows Update or enterprise patch management systems. After patching, verify print functionality remains operational and test that the privilege escalation vector is no longer exploitable.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

Windows 10 21h2Operating system

Affected:< 10.0.19044.5737

Windows 10 22h2Operating system

Affected:< 10.0.19045.5737

Windows 11 22h2Operating system

Affected:< 10.0.22621.5189

Windows 11 23h2Operating system

Affected:< 10.0.22631.5189

Windows 11 24h2Operating system

Affected:< 10.0.26100.3775

Windows Server 2022Operating system

Affected:< 10.0.20348.3453

Windows Server 2022 23h2Operating system

Affected:< 10.0.25398.1551

Windows Server 2025Operating system

Affected:< 10.0.26100.3775

CVSS breakdown

From the vector

Attack vector: Local
Complexity: Low
Privileges: Low
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

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

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Check Windows version against affected ranges

Run 'winver' or 'systeminfo' from command prompt, or use PowerShell: [Environment]::OSVersion or Get-ComputerInfo OsVersion

Affected if The installed Windows version falls below any of these thresholds: Windows 10 21h2 < 10.0.19044.5737, Windows 10 22h2 < 10.0.19045.5737, Windows 11 22h2 < 10.0.22621.5189, Windows 11 23h2 < 10.0.22631.5189, Windows 11 24h2 < 10.0.26100.3775, Server 2022 < 10.0.20348.3453, Server 2022 23h2 < 10.0.253
Verify USB printing capability is present

Check for usbprint.sys driver file in C:\Windows\System32\drivers\ or run 'pnputil /enum-drivers' to list installed printer drivers

Affected if The usbprint.sys driver exists on the system, indicating the USB Print Driver component is available
Check for active USB printers

Open Devices and Printers from Control Panel or run 'Get-Printer * | Where-Object {$_.PortName -match "USB"}' in PowerShell to enumerate printers using USB ports

Affected if Any printer is connected via USB and configured, making the vulnerable code path potentially reachable
Confirm Print Spooler service status

Run 'Get-Service Spooler' in PowerShell or check Services.msc for the Print Spooler service

Affected if The Print Spooler service is running, which loads and uses the USB print driver for USB printer communications

The system is affected if it runs an unpatched Windows version within the affected ranges AND has the USB Print Driver component present with USB printing capability enabled.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Upgrade available Upgrade to 10.0.19044.5737 / 10.0.19045.5737 / 10.0.20348.3453 or later

Fixed in 10.0.19044.573710.0.19045.573710.0.20348.3453

Interim mitigation

Apply the Microsoft security update for CVE-2025-26639 through standard Windows Update or enterprise patch management systems. After patching, verify print functionality remains operational and test that the privilege escalation vector is no longer exploitable.

Recommended fix High confidence

Upgrade to the minimum fixed build: Windows 10 21h2 (10.0.19044.5737), Windows 10 22h2 (10.0.19045.5737), Windows 11 22h2 (10.0.22621.5189), Windows 11 23h2 (10.0.22631.5189), Windows 11 24h2 (10.0.26100.3775), Windows Server 2022 (10.0.20348.3453), Windows Server 2022 23h2 (10.0.25398.1551), Window

1. Identify the current Windows version by running `winver` or checking System Information
2. For Windows 10 21h2: upgrade to version 10.0.19044.5737 or later via Windows Update or ISO
3. For Windows 10 22h2: upgrade to version 10.0.19045.5737 or later via Windows Update or ISO
4. For Windows 11 22h2: upgrade to version 10.0.22621.5189 or later via Windows Update or ISO
5. For Windows 11 23h2: upgrade to version 10.0.22631.5189 or later via Windows Update or ISO
6. For Windows 11 24h2: upgrade to version 10.0.26100.3775 or later via Windows Update or ISO
7. For Windows Server 2022: upgrade to version 10.0.20348.3453 or later via Windows Update or WSUS
8. For Windows Server 2022 23h2: upgrade to version 10.0.25398.1551 or later via Windows Update or WSUS

Caveat Standard Windows cumulative updates carry minimal risk; ensure backups and test in staging if possible

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 10 21h2 Scoped from the published advisory

Consultation2.0 h
Implementation1.0 h
Testing2.0 h
Review / QA1.0 h

6.0 hours of engineering $1,060

Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

Scan for this in your stack

Free · runs locally

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References

Primary sources

msrc.microsoft.comVendor Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-26639 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2025-26639?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsUpgrade to 10.0.19044.5737 / 10.0.19045.5737 or later

Severity 7.8 High

Exploit likelihood EPSS, next 30 days 0.5%

Affects: Windows 10 21h2

Remediation

A high-priority fix

Fix this in Windows 10 21h2 6 hrs · Moderate

Typical engagement from $1,060

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2025-26639 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References