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CVE-2026-21513

HIGH 8.8 KNOWN EXPLOITED ALL-YEARS

Published 2026-02-10 · Last modified 2026-08-19 · microsoft · NVD: Analyzed

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

ACTIVELY EXPLOITED

Confirmed exploited in the wild — in CISA KEV since 2026-02-10. Patch or mitigate now.

Exploitation likelihood

15.9%chance of exploitation in 30 days · 97th percentile

● In CISA KEV (2026-02-10)○ Catalogued PoC◆ SSVC: exploitation active, automatable no

Impact if exploited

8.8CVSS 3.1 · HIGH · CNA

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ⚠User interaction: A user must take an action (click / open a file)
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

Search GitHub now — results may be empty or unverified.

Tracked sources are checked weekly for the full archive, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Affected

Vendors Microsoft

Products Windows 10 Version 1607 Windows 10 Version 1809 Windows 10 Version 21h2 Windows 10 Version 22h2 Windows 11 Version 22h3 Windows 11 Version 23h2 Windows 11 Version 24h2 Windows 11 Version 25h2 Windows 11 Version 26h1 Windows Server 2012 Windows Server 2012 (Server Core Installation) Windows Server 2012 R2 Windows Server 2012 R2 (Server Core Installation) Windows Server 2016 Windows Server 2016 (Server Core Installation) Windows Server 2019 Windows Server 2019 (Server Core Installation) Windows Server 2022 Windows Server 2022, 23h2 Edition (Server Core Installation) Windows Server 2025 Windows Server 2025 (Server Core Installation) Windows 10 1607 Windows 10 1809 Windows 10 21h2 Windows 10 22h2 Windows 11 23h2 Windows 11 24h2 Windows 11 25h2 Windows Server 2022 23h2

Weakness (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/E:U/RL:O/RC:C

References and research data (JSON)

Additional exploitation reports

Source-specific reports, separate from CISA KEV. Repeated observations from one source are not independent confirmations.

2 more source reports

Known Affected Software Configurations

VendorProductVersion range
MicrosoftWindows 10 1607< 10.0.14393.8868
MicrosoftWindows 10 1607< 10.0.14393.8868
MicrosoftWindows 10 1809< 10.0.17763.8389
MicrosoftWindows 10 1809< 10.0.17763.8389
MicrosoftWindows 10 21h2< 10.0.19044.6937
MicrosoftWindows 10 21h2< 10.0.19044.6937
MicrosoftWindows 10 21h2< 10.0.19044.6937
MicrosoftWindows 10 22h2< 10.0.19045.6937
MicrosoftWindows 10 22h2< 10.0.19045.6937
MicrosoftWindows 10 22h2< 10.0.19045.6937
MicrosoftWindows 11 23h2< 10.0.22631.6649
MicrosoftWindows 11 23h2< 10.0.22631.6649
MicrosoftWindows 11 24h2< 10.0.26100.7781
MicrosoftWindows 11 24h2< 10.0.26100.7781
MicrosoftWindows 11 25h2< 10.0.26200.7781
MicrosoftWindows 11 25h2< 10.0.26200.7781
MicrosoftWindows Server 2012*
MicrosoftWindows Server 2012r2
MicrosoftWindows Server 2016< 10.0.14393.8868
MicrosoftWindows Server 2019< 10.0.17763.8389
MicrosoftWindows Server 2022< 10.0.20348.4711
MicrosoftWindows Server 2022 23h2< 10.0.25398.2149
MicrosoftWindows Server 2025< 10.0.26100.32313

All CVSS metrics

  • HIGH 8.8 v3.1 · CNA Primary
    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
  • HIGH 8.8 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

Patches & mitigations

Advisories

Technical & other

Sources: NVD · CVE.org · All sources and attribution · EPSS