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CVE-2026-45458 is a Critical remote code execution vulnerability affecting Microsoft Outlook and Microsoft Word. The provided content consistently describes the flaw as a memory-safety issue in the Word rendering engine used by Outlook Classic to render email content, including in the Preview Pane. More specifically, multiple supporting contexts identify CVE-2026-45458 as a use-after-free condition in the Office document parsing/rendering pipeline, where freed memory may later be dereferenced after being reallocated with attacker-controlled data. Because Outlook Classic relies on Word functionality for message rendering, a specially crafted email body or document can trigger the vulnerable code path during rendering, including via the Preview Pane without the victim explicitly opening an attachment or enabling macros. Successful exploitation results in arbitrary code execution in the security context of the victim user.
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A critical remote code execution vulnerability caused by a use-after-free flaw in the Microsoft Word rendering engine, affecting Outlook and Word via email/document rendering, including the Outlook Preview Pane.
A critical remote code execution vulnerability in Microsoft Outlook and Word caused by a use-after-free flaw in the Word rendering engine/document parsing pipeline.
Critical Outlook and Word remote code execution vulnerability with a working Preview Pane attack vector, making it high priority for patching.
A critical type confusion remote code execution vulnerability in Microsoft Office exploitable via the Outlook Classic preview pane.
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Every observed campaign linking this CVE to a named adversary.
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Cross-references every affected SKU, including bundled OEM variants.
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