Russian hackers are exploiting recently patched Microsoft Office vulnerability (CVE-2026-21509)

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Russian hackers are exploiting recently patched Microsoft Office vulnerability (CVE-2026-21509)

Helpnetsecurity • February 3, 2026

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Russian hackers Fancy Bear (aka APT 28) are exploiting CVE-2026-21509, for which Microsoft released an emergency fix last week.

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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 (2)

APT 28 Fancy Bear

CVEs (1)

Platforms (1)

Microsoft Office