CVE-2026-21509: APT28 Actively Exploits Microsoft Office Vulnerability in Ukraine

Socradar • February 3, 2026

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On January 26, 2026, Microsoft released an update to address CVE-2026-21509, a high-severity vulnerability affecting nearly every modern version ...

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Cyberattacks Target Ukraine and EU via Microsoft Office Vulnerability CERT-UA has reported a new wave of cyberattacks targeting Ukrainian government agencies and EU organizations, exploiting the Microsoft Office vulnerability CVE-2026-21509. Attackers are using malicious emails disguised as communications from the Ukrainian Hydrometeorological Center to gain access to victims' systems. 59 sources 50

Extracted Entities

APT Groups (1)

Attack Types (1)

Zero-day Exploit

Countries (1)

CVEs (1)

Platforms (1)

Microsoft Office