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CVE-2026-20953 is a critical use-after-free vulnerability in Microsoft Office. The flaw arises from improper handling of object lifetime in Office memory management, creating a condition in which freed memory can be reused in a way that permits attacker-controlled execution flow. Microsoft and multiple contemporaneous reports classify the issue as a remote code execution vulnerability affecting Microsoft Office product lines including Office 2016, Office 2019, Office LTSC 2021, Office LTSC 2024, Microsoft 365 Apps for Enterprise, and Office LTSC for Mac 2021 and 2024. Available reporting indicates exploitation can be triggered through a specially crafted Office document, and the Preview Pane is described as a valid attack vector, reducing or in some scenarios eliminating the need for a victim to explicitly open the malicious file. Successful exploitation results in code execution in the context of the affected Office process and logged-on user.
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24 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Critical Microsoft Office remote code execution via maliciously crafted Office files; includes an Outlook preview-pane exploitation vector per the content.
A Microsoft Office use-after-free enabling local arbitrary code execution, with some attack paths requiring little/no user interaction (including Preview Pane rendering).
A Microsoft Office use-after-free enabling local arbitrary code execution, with some attack paths requiring little/no user interaction (including Preview Pane rendering).
A critical remote code execution vulnerability in Microsoft Office triggered via a malicious Office document (potentially exploitable via Outlook Preview Pane per the content).
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.