Ukrainian CERT Warns of Active Russian Exploitation of Recently Patched Microsoft Office Vulnerability

The Ukrainian Computer Emergency Response Team (CERT) reports that Russian hackers are actively exploiting the vulnerability CVE-2026-21509, a recently patched flaw affecting multiple versions of Microsoft Office. No specific dates for exploitation or patching are mentioned. The vulnerability allows for remote exploitation, but technical details and concrete impacts are not specified in the excerpt. The alert comes from Ukrainian authorities in the context of ongoing cyberattacks linked to the current conflict.