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ExploitedIn CISA KEVFix available

CVE-2026-21513

MSHTML Framework Security Feature Bypass Vulnerability

Exploitation confirmed. First attested on 2026-02-10 by CISA-ADP, CISA KEV, GCVE · kevintel.

  • Published2026-02-10
  • WeaknessCWE-693

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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

Timeline

dates in UTC
  1. 2026-02-10Added to the CISA KEV catalogCISA KEV
  2. 2026-02-10Listed as exploited by GCVEGCVE
  3. 2026-02-10Exploitation first reportedCISA KEV
  4. 2026-02-1018:16CVE publishedNVD
  5. 2026-02-1104:55SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-09 03:37 UTC
Indicators tagged with this CVE, per day1 indicator over 7 days
06
IndicatorSeen
42533fbb40fe274c96a31c948ae6e84b6c103f9da6f27c9d1dc5c011f7b719d03 days ago
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-21513?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-21513?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Microsoft windows server 2012
BranchAffectedFixed in
—all versionsno fix published
—= r2no fix published
Microsoft windows 10 1607
BranchAffectedFixed in
10.0< 10.0.14393.886810.0.14393.8868
Microsoft windows 10 1809
BranchAffectedFixed in
10.0< 10.0.17763.838910.0.17763.8389

10 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA22 products

As microsoft, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Microsoft Windows 10 Version 1607

    platforms: 32-bit Systems, x64-based Systems

    Affected
    • ≥ 10.0.14393.0, < 10.0.14393.8868fixed in 10.0.14393.8868custom
  • Microsoft Windows 10 Version 1809

    platforms: 32-bit Systems, x64-based Systems

    Affected
    • ≥ 10.0.17763.0, < 10.0.17763.8389fixed in 10.0.17763.8389custom
  • Microsoft Windows 10 Version 21H2

    platforms: 32-bit Systems, ARM64-based Systems, x64-based Systems

    Affected
    • ≥ 10.0.19044.0, < 10.0.19044.6937fixed in 10.0.19044.6937custom
  • Microsoft Windows 10 Version 22H2

    platforms: 32-bit Systems, ARM64-based Systems, x64-based Systems

    Affected
    • ≥ 10.0.19045.0, < 10.0.19045.6937fixed in 10.0.19045.6937custom
  • Microsoft Windows 11 version 22H3

    platforms: ARM64-based Systems

    Affected
    • ≥ 10.0.22631.0, < 10.0.22631.6649fixed in 10.0.22631.6649custom
  • Microsoft Windows 11 Version 23H2

    platforms: x64-based Systems

    Affected
    • ≥ 10.0.22631.0, < 10.0.22631.6649fixed in 10.0.22631.6649custom

16 more products in the CVE record.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-08-19

Fix

  1. CISA’s required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.due 2026-03-03

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2026-02-10
Patch Due Date
2026-03-03
Ransomware Use
Unknown
Required Action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
2026-02-10
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-rqf6-jf48-p6rm

Frequently asked questions

What is CVE-2026-21513?

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

Is CVE-2026-21513 actively exploited?

Yes. CVE-2026-21513 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2026-03-03.

What is the CVSS score for CVE-2026-21513?

CVE-2026-21513 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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Sources for this record