Vulnerabilities · 242 days ago

APT28 exploited MSHTML zero-day against Windows systems

Russia-linked APT28 exploited MSHTML vulnerability CVE-2026-21513 to bypass security controls via crafted LNK and HTML files and potentially enable code execution on Windows.

CVE-2026-21513

NVD KEV

Known exploited · CISA KEV

CVSS 8.8 HIGH: protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a… EPSS 16% (97th percentile). Microsoft patch: 5077179.

Patch available KB5077179 Download →

CISA federal remediation date Mar 3

Timeline

Mar 3 CISA federal deadline for CVE-2026-21513
Mar 2 Reported by The Hacker News
Feb 10 CVE-2026-21513 added to CISA KEV

Sources

1 source covering this story

The Hacker News Mar 2
APT28 Tied to CVE-2026-21513 MSHTML 0-Day Exploited Before Feb 2026 Patch Tuesday
APT28 exploited CVE-2026-21513, an MSHTML zero-day (CVSS 8.8), using malicious LNK files to bypass security controls and execute code.

Entities

CVE-2026-21513
APT28

Vendor digest: Microsoft

Part of the PlainSec briefing for 2026-03-03

Editions

Briefing for 2026-03-03