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CVE-2026-20955 is a remote code execution vulnerability in Microsoft Excel caused by an untrusted pointer dereference during processing of a crafted Excel file. The flaw is memory-safety related and can be triggered when Excel parses malicious spreadsheet content, leading to execution of attacker-controlled code in the security context of the logged-on user. Available reporting characterizes the issue as affecting Excel specifically, with exploitation requiring the target to open a malicious file; the Preview Pane is not identified as a viable attack vector for this vulnerability.
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No public exploit code observed for this vulnerability.
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
14 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Critical Microsoft Excel remote code execution via maliciously crafted Office files (memory-related) per the content.
A Microsoft Excel RCE caused by untrusted pointer dereference during file parsing, enabling arbitrary code execution when a user opens a crafted spreadsheet.
A Microsoft Excel RCE caused by untrusted pointer dereference during file parsing, enabling arbitrary code execution when a user opens a crafted spreadsheet.
A severe vulnerability affecting Microsoft Office (details not provided in 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.