Vulnerabilities & Exploits · Zero-Day Exploit
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.
1 source · Mar 2
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
The Hacker News
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.
originalPart of the PlainSec briefing for 2026-03-03
Every edition of this story: APT28 Exploited MSHTML Zero-Day Against Windows Systems