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CVE-2026-21513

MSHTML Framework Security Feature Bypass Vulnerability

Exploited in the wild. In CISA KEV since 2026‑02‑10. A vendor fix is available.

CVSS 3.18.8HighEPSS percentile97th16% chance in 30 daysCISA KEVListedsince 2026-02-10, due 2026-03-03
No public exploit knownFixVendor fixNo build named by the sources

Published Updated Sources: CVE.org, NVD, BDU

NVD CVE.org

What to do

The vendor has published a fix. Version details are below where the sources state them.

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

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

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS97th
CISA KEV
CISA KEV

Listed as exploited in the wild since 2026-02-10.

US federal agencies must remediate by 2026-03-03.

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

16% chance of exploitation activity in the next 30 days, which ranks it in the 97th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

7 events over 135 days, from the signal feeds we watch.

  1. OpenVAS check added
  2. EPSS band changelow → moderate
  3. Patch availablerecord updated
  4. Added to CISA KEVpublished, weakness classified

Affected products

And 48 more affected products. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 8.8 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required NoneNo authentication required — anyone can exploit this
  • User Interaction RequiredA user must click a link, open a file, or perform some action

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality HighTotal information disclosure — all data in the component is compromised
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

Sources

References in the record

In the news

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We'll flag the next CVE, public exploit or patch for Windows 10 Version 1607, not every advisory. This one: actively exploited.

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