APT28 Weaponized That Office Zero-Day in Three Days Flat
Russia's APT28 began exploiting Microsoft Office CVE-2026-21509 just 72 hours after disclosure, targeting Ukraine, Slovakia, and Romania with email-stealing malware and Covenant implants.
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Updated September 11, 2026 — all 201 published advisories are browsable here. The newest one is on the appliance that is supposed to be doing the protecting: a Cisco firewall management flaw under active attack and added to CISA's known-exploited list, on the console that controls the firewalls guarding the whole network (CVE-2026-20079). Behind it, a Chrome zero-day exploited in the wild, where simply visiting a booby-trapped site is enough to get code running on the machine (CVE-2026-87491), and a FreeIPA flaw that hands full administrator rights to anyone who connects without a password, on the directory server that decides who gets into everything else (CVE-2026-76578). The one readers keep coming back to is the Magento and Adobe Commerce zero-day being exploited against live online stores with no vendor patch available (StyleSmuggler). Every one of these sits on a device or service that faces the internet, so the clock starts the day the advisory drops — and a missed patch window is what turns a routine Tuesday into downtime, a breach-notification bill, and lost revenue. If you are not sure whether yours is patched, our 24/7 staffed security operations center handles the triage for you.
Russia's APT28 began exploiting Microsoft Office CVE-2026-21509 just 72 hours after disclosure, targeting Ukraine, Slovakia, and Romania with email-stealing malware and Covenant implants.
A high-severity Microsoft Office zero-day (CVE-2026-21509) is being actively exploited to bypass security controls designed to block risky COM and OLE content. Successful exploitation requires a user to open a malicious Office document, enabling follow-on payload execution and intrusion activity. Apply Microsoft's out-of-band update immediately or deploy the recommended registry-based mitigation if patching is delayed.
Read moreReact2Shell refers to a newly disclosed set of exploitation paths affecting React Server Components and modern server-side rendering workflows. In vulnerable implementations, attackers may escalate from user-driven application behavior into sensitive server-side execution, data access, or compromise of backend services. Organizations using RSC or SSR patterns should audit server-executed components, reduce dynamic execution paths, and apply strict validation and least-privilege controls.
Read moreOur CyberOne MobileAssess platform performs deep static analysis, source code decompilation, and runtime security testing for iOS and Android apps. From one-time assessments to year-long continuous testing, we find what surface-level scanners miss.
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