Microsoft has issued emergency, out-of-band security updates to address a high-severity zero-day vulnerability in Microsoft Office that is already being exploited in real-world attacks, underscoring the persistent security challenges facing one of the world\u2019s most widely deployed productivity platforms.<\/p>\n\n\n\n
The flaw, tracked as CVE-2026-21509<\/strong><\/a>, is classified as a security feature bypass<\/em> vulnerability and affects a broad range of Office products, including Microsoft Office 2016<\/strong>, Office 2019<\/strong>, Office LTSC 2021<\/strong>, Office LTSC 2024<\/strong>, and Microsoft 365 Apps for Enterprise<\/strong>. According to Microsoft, the vulnerability allows attackers to circumvent built-in protections designed to block unsafe COM and OLE controls\u2014components that have long been a favored attack surface for malicious actors.<\/p>\n\n\n(1) Microsoft Rushes Emergency Fix For Actively Exploited Office Zero-Day | LinkedIn<\/a>: Microsoft Rushes Emergency Fix For Actively Exploited Office Zero-Day<\/span><\/a>","protected":false},"excerpt":{"rendered":" Microsoft has issued emergency, out-of-band security updates to address a high-severity zero-day vulnerability in Microsoft Office that is already being exploited in real-world attacks, underscoring the persistent security challenges facing one of the world\u2019s most widely deployed productivity platforms. The flaw, tracked as CVE-2026-21509, is classified as a security feature…<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[72],"class_list":["post-891","post","type-post","status-publish","format-standard","hentry","category-vulnerability","tag-72"],"_links":{"self":[{"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/posts\/891","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/comments?post=891"}],"version-history":[{"count":1,"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/posts\/891\/revisions"}],"predecessor-version":[{"id":892,"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/posts\/891\/revisions\/892"}],"wp:attachment":[{"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/media?parent=891"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/categories?post=891"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/familiebuckens.nl\/index.php\/wp-json\/wp\/v2\/tags?post=891"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}