Widely used Windows MSHTML framework; network-based protection bypass; broad impact.
CVE-2026-21513
MSHTML: protection mechanism bypass via network.
Is CVE-2026-21513 being exploited?
Yes. CVE-2026-21513 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2026-21513?
CVE-2026-21513 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-21513?
Yes. A fix has been recorded for CVE-2026-21513. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-21513 affect?
CVE-2026-21513 affects Windows MSHTML Framework (Edge/IE rendering). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-21513?
Apply vendor mitigations; monitor advisories; patch when released
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote bypass of a security feature in MSHTML over the network; could enable broader compromise.
Patch when possible
- affected>= 10.0.14393.0 and < 10.0.14393.8868
- affected>= 10.0.17763.0 and < 10.0.17763.8389
- affected>= 10.0.19044.0 and < 10.0.19044.6937
- affected>= 10.0.19045.0 and < 10.0.19045.6937
- affected>= 10.0.22631.0 and < 10.0.22631.6649
- affected>= 10.0.22631.0 and < 10.0.22631.6649
- affected>= 10.0.26100.0 and < 10.0.26100.7840
- affected>= 10.0.26200.0 and < 10.0.26200.7840
- affected>= 10.0.28000.0 and < 10.0.28000.1575
- affected>= 10.0.28000.0 and < 10.0.28000.1575
- affected>= 6.2.9200.0 and < 6.2.9200.25923
- affected>= 6.3.9600.0 and < 6.3.9600.23022
- affected>= 6.3.9600.0 and < 6.3.9600.23022
- affected>= 6.2.9200.0 and < 6.2.9200.25923
- affected>= 10.0.14393.0 and < 10.0.14393.8868
- affected>= 10.0.14393.0 and < 10.0.14393.8868
- affected>= 10.0.17763.0 and < 10.0.17763.8389
- affected>= 10.0.17763.0 and < 10.0.17763.8389
- affected>= 10.0.20348.0 and < 10.0.20348.4773
- affected>= 10.0.25398.0 and < 10.0.25398.2149
- affected>= 10.0.26100.0 and < 10.0.26100.32370
- affected>= 10.0.26100.0 and < 10.0.26100.32370
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.