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CVE-2026-55129 is a critical heap-based buffer overflow vulnerability in Microsoft Office that can lead to remote code execution. The flaw affects multiple supported Microsoft Office editions, including Microsoft 365 Apps for Enterprise, Office 2016, Office 2019, Office LTSC 2021, Office LTSC 2024, and Office for Mac. Exploitation occurs when Office processes specially crafted content, typically delivered in a malicious document. Opening the crafted file can trigger memory corruption and allow arbitrary code execution in the security context of the logged-on user. The Preview Pane is also an attack vector, meaning exploitation may occur during document preview rather than full opening.
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No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A critical remote code execution vulnerability affecting multiple Microsoft Office editions, triggered by specially crafted content.
A critical remote code execution vulnerability in Microsoft Office.
A critical remote code execution vulnerability in Microsoft Office, typically triggered by opening a specially crafted document.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.