CVE-2026-21513: listed in the CISA KEV catalog

CVE-2026-21513 · CVSS 8.8 HIGH · EPSS 15% · KEV 2026-02-10 · patch available

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

Is CVE-2026-21513 exploited?

• Listed in the CISA KEV catalog on 2026-02-10.
• Federal remediation due 2026-03-03.
• Past that date by 165 days.
• EPSS puts exploitation in the next 30 days at 15%.
• Public exploit code: none found in monitored sources.

Which products and versions are affected?

No affected package list recorded here yet.

Is there a patch?

• KB5077179
• KB5075904
• KB5075906
• KB5075943
• KB5075912
• KB5075899
• KB5075942
• KB5077181
• KB5077212
• KB5075941

What PlainSec published about CVE-2026-21513

• APT28 Expands Supply-Chain Attacks Using Fresh Office Zero-Days (2026-04-09)
• APT28 Tied to CVE-2026-21513 MSHTML 0-Day Exploited Before Feb 2026 Patch Tuesday (2026-03-03)

Primary sources

• NVD record
• CISA KEV catalog
• Microsoft KB5077179
• Microsoft KB5075904
• Microsoft KB5075906
• Microsoft KB5075943
• Microsoft KB5075912
• Microsoft KB5075899
• Microsoft KB5075942
• Microsoft KB5077181

What this record does not say

• No affected package data.

KEV and EPSS are re-checked daily. Record last updated 2026-08-11.