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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 16 May 2022.
Windows 10 2004Operating system · Microsoft

CVE-2021-41357

HIGH · 7.8 CVSS v3.1 Developing Published 2021-10-13
Fix available
A fix is available. Upgrade to 10.0.19041.1288 / 10.0.19042.1288 or later.
See remediation →
96/100
Remediation priority · Urgent
In the wild Zero-click Patch available

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.

NVD · unedited
Win32k Elevation of Privilege Vulnerability

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.

dbcve analysis · low confidence
Developing — this CVE was published recently and its authoritative NVD entry is still being established, so we're holding a technical summary until the source data settles rather than publish something unreliable. Re-checking after 2026-08-23.

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.

NVD · CPE data
Windows 10 2004Operating system
Affected:< 10.0.19041.1288
Windows 10 20h2Operating system
Affected:< 10.0.19042.1288
Windows 10 21h1Operating system
Affected:< 10.0.19043.1288
Windows 11 21h2Operating system
Affected:< 10.0.22000.258
Windows Server 2004Operating system
Affected:< 10.0.19041.1288
Windows Server 2022Operating system
Affected:< 10.0.20348.288
Windows Server 20h2Operating system
Affected:< 10.0.19042.1288

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.

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

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.

dbcve · scoped
Upgrade available Upgrade to 10.0.19041.1288 / 10.0.19042.1288 / 10.0.19043.1288 or later
Fixed in 10.0.19041.128810.0.19042.128810.0.19043.1288
Vendor patch portal.msrc.microsoft.com →
Recommended fix High confidence

Microsoft Security Update (CVE-2021-41357) - specific build numbers per version (e.g., Windows 10 2004: 10.0.19041.1288, Windows 10 20h2: 10.0.19042.1288, Windows 10 21h1: 10.0.19043.1288, Windows 11 21h2: 10.0.22000.258, Windows Server 2022: 10.0.20348.288)

  1. Open Windows Update by clicking Start > Settings > Update & Security > Windows Update
  2. Click 'Check for updates' to find the appropriate security update
  3. Install the cumulative security update for your Windows version that includes the Win32k fix
  4. For Windows 10 2004: Ensure update brings build to 10.0.19041.1288 or later
  5. For Windows 10 20h2: Ensure update brings build to 10.0.19042.1288 or later
  6. For Windows 10 21h1: Ensure update brings build to 10.0.19043.1288 or later
  7. For Windows 11 21h2: Ensure update brings build to 10.0.22000.258 or later
  8. For Windows Server 2004: Ensure update brings build to 10.0.19041.1288 or later
Caveat Standard Windows update risks - ensure backups and test in staging if possible

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

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get it fixed fast

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

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-41357 in production — separate from our analysis above.

No notes yet

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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