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NVD / CVE Program· CNA microsoft

CVE-2026-21513: MSHTML Framework Security Feature Bypass Vulnerability

HighCVSS 8.8 · v3.1KEVWeaponized Fix available

Noroxi assessment

Priority: This week (action score 70/100)

  • CISA has confirmed exploitation in the wild (Feb 10, 2026). Remediation deadline for US federal agencies: Mar 3, 2026.
  • Probability of exploitation in the next 30 days: 15.8% (FIRST EPSS); higher than 96.9% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: Windows 10 Version 1607 for 32-bit Systems 10.0.14393.8868; Windows 10 Version 1607 for x64-based Systems 10.0.14393.8868; Windows 10 Version 1809 for 32-bit Systems 10.0.17763.8389.

Don’t wait for the next maintenance window. Upgrade to Windows 10 Version 1607 for 32-bit Systems 10.0.14393.8868; Windows 10 Version 1607 for x64-based Systems 10.0.14393.8868; Windows 10 Version 1809 for 32-bit Systems 10.0.17763.8389 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS

Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.

Published
Feb 10, 2026
Updated
Aug 19, 2026
EPSS
15.8% · 96th percentile

Report tools

JSON

Action score

70

This week

Don’t wait for the next maintenance window.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
30 / 30 · Listed
EPSS
5 / 30 · 15.8%

CISA SSVC decision

Exploitation
active
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · microsoft
8.8
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Feb 10, 2026. That signals real attacks, not theory.

Remediation deadline for US federal agencies: Mar 3, 2026.

Get told when this record changes

  • In CISA KEV: exploitation in the wild confirmed
  • Weaponized exploit exists
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-21513

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
microsoftwindows 10 1607
microsoftwindows 10 1809
microsoftwindows 10 21h2
microsoftwindows 10 22h2
microsoftwindows 11 23h2
microsoftwindows 11 24h2
microsoftwindows 11 25h2
microsoftwindows server 2012
microsoftwindows server 2016
microsoftwindows server 2019
microsoftwindows server 2022
microsoftwindows server 2022 23h2

and 1 more

Versions reported by the vendor

Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.

  • Microsoft Windows 10 Version 1607

    • 10.0.14393.0 and later · before 10.0.14393.8868affected

  • Microsoft Windows 10 Version 1809

    • 10.0.17763.0 and later · before 10.0.17763.8389affected

  • Microsoft Windows 10 Version 21H2

    • 10.0.19044.0 and later · before 10.0.19044.6937affected

  • Microsoft Windows 10 Version 22H2

    • 10.0.19045.0 and later · before 10.0.19045.6937affected

  • Microsoft Windows 11 version 22H3

    • 10.0.22631.0 and later · before 10.0.22631.6649affected

  • Microsoft Windows 11 Version 23H2

    • 10.0.22631.0 and later · before 10.0.22631.6649affected

  • Microsoft Windows 11 Version 24H2

    • 10.0.26100.0 and later · before 10.0.26100.7840affected

  • Microsoft Windows 11 Version 25H2

    • 10.0.26200.0 and later · before 10.0.26200.7840affected

  • Microsoft Windows 11 version 26H1

    • 10.0.28000.0 and later · before 10.0.28000.1575affected

  • Microsoft Windows 11 Version 26H1

    • 10.0.28000.0 and later · before 10.0.28000.1575affected

  • Microsoft Windows Server 2012

    • 6.2.9200.0 and later · before 6.2.9200.25923affected

  • Microsoft Windows Server 2012 (Server Core installation)

    • 6.2.9200.0 and later · before 6.2.9200.25923affected
Affected versions · NVD (7)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • microsoft windows server 2012all versions
  • microsoft windows server 2012r2
  • microsoft windows server 2016before 10.0.14393.8868
  • microsoft windows server 2019before 10.0.17763.8389
  • microsoft windows server 2022before 10.0.20348.4711
  • microsoft windows server 2022 23h2before 10.0.25398.2149
  • microsoft windows server 2025before 10.0.26100.32313

Same product

microsoft: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-33824Windows Internet Key Exchange (IKE) Service Extensions Remote Code Execution VulnerabilityKEV
    92Now
  • CVE-2018-8174A remote code execution vulnerability exists in the way that the VBScript engine handles objects in memory, aka "Windows VBScript Engine…KEV
    86Now
  • CVE-2026-21510Windows Shell Security Feature Bypass VulnerabilityKEV
    83Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-21255Feb 10, 2026 · Windows Hyper-V Security Feature Bypass Vulnerability
    35Monitor
  • ← EarlierCVE-2026-21508Feb 10, 2026 · Windows Storage Elevation of Privilege Vulnerability
    28Monitor
  • Later →CVE-2026-21519Feb 10, 2026 · Desktop Window Manager Elevation of Privilege VulnerabilityKEV
    62This week

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Windows 10 Version 1607 for 32-bit Systems10.0.14393.8868 · KB5075999Microsoft (MSRC)
Windows 10 Version 1607 for x64-based Systems10.0.14393.8868 · KB5075999Microsoft (MSRC)
Windows 10 Version 1809 for 32-bit Systems10.0.17763.8389 · KB5075904Microsoft (MSRC)
Windows 10 Version 1809 for x64-based Systems10.0.17763.8389 · KB5075904Microsoft (MSRC)
Windows 10 Version 21H2 for 32-bit Systems10.0.19044.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 21H2 for ARM64-based Systems10.0.19044.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 21H2 for x64-based Systems10.0.19044.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 22H2 for 32-bit Systems10.0.19045.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 22H2 for ARM64-based Systems10.0.19045.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 22H2 for x64-based Systems10.0.19045.6937 · KB5075912Microsoft (MSRC)
Windows 11 Version 23H2 for ARM64-based Systems10.0.22631.6649 · KB5075941Microsoft (MSRC)
Windows 11 Version 23H2 for x64-based Systems10.0.22631.6649 · KB5075941Microsoft (MSRC)
Windows 11 Version 24H2 for ARM64-based Systems10.0.26100.7781 · KB5077212Microsoft (MSRC)
Windows 11 Version 24H2 for ARM64-based Systems10.0.26100.7840 · KB5077181Microsoft (MSRC)
Windows 11 Version 24H2 for x64-based Systems10.0.26100.7781 · KB5077212Microsoft (MSRC)
Windows 11 Version 24H2 for x64-based Systems10.0.26100.7840 · KB5077181Microsoft (MSRC)
Windows 11 Version 25H2 for ARM64-based Systems10.0.26200.7781 · KB5077212Microsoft (MSRC)
Windows 11 Version 25H2 for ARM64-based Systems10.0.26200.7840 · KB5077181Microsoft (MSRC)
Windows 11 Version 25H2 for x64-based Systems10.0.26200.7781 · KB5077212Microsoft (MSRC)
Windows 11 Version 25H2 for x64-based Systems10.0.26200.7840 · KB5077181Microsoft (MSRC)
Windows 11 Version 26H1 for ARM64-based Systems10.0.28000.1575 · KB5077179Microsoft (MSRC)
Windows 11 version 26H1 for x64-based Systems10.0.28000.1575 · KB5077179Microsoft (MSRC)
Windows Server 20126.2.9200.25923 · KB5075971Microsoft (MSRC)
Windows Server 2012 (Server Core installation)6.2.9200.25923 · KB5075971Microsoft (MSRC)
Windows Server 2012 R26.3.9600.23022 · KB5075970Microsoft (MSRC)
Windows Server 2012 R2 (Server Core installation)6.3.9600.23022 · KB5075970Microsoft (MSRC)
Windows Server 201610.0.14393.8868 · KB5075999Microsoft (MSRC)
Windows Server 2016 (Server Core installation)10.0.14393.8868 · KB5075999Microsoft (MSRC)
Windows Server 201910.0.17763.8389 · KB5075904Microsoft (MSRC)
Windows Server 2019 (Server Core installation)10.0.17763.8389 · KB5075904Microsoft (MSRC)

+9

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. CISA KEV-1 d
  2. Published
  3. TodayNov 12, 2026+275 d

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-215100 days apartWindows Shell Security Feature Bypass VulnerabilityKEV
    83Now
  • CVE-2026-3220263 days apartWindows Shell Spoofing VulnerabilityKEV
    68This week
  • CVE-2026-3222563 days apartWindows Shell Security Feature Bypass Vulnerability
    35Monitor
  • CVE-2026-45656119 days apartUEFI Secure Boot Security Feature Bypass Vulnerability
    31Monitor
  • CVE-2026-48570119 days apartSecure Boot Security Feature Bypass Vulnerability
    31Monitor
  • CVE-2026-48575119 days apartSecure Boot Security Feature Bypass Vulnerability
    31Monitor

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-693 · Protection Mechanism Failure

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records