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CVE-2026-81391 is a use-of-uninitialized-resource vulnerability in Microsoft Office Excel. Improper use of an uninitialized resource can expose uninitialized stack memory to a local unauthorized attacker, resulting in information disclosure. Microsoft rates the vulnerability Important with a CVSS 3.1 base score of 5.5.
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What an attacker gets, and what they’ve been doing with it.
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Patch, then assume compromise.
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No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Microsoft Excel vulnerability referenced by the security-update plugin; technical details are not provided.
Microsoft Office Excel uninitialized-resource local information-disclosure vulnerability.
A Microsoft Excel vulnerability addressed by MS26-5002914; no technical details are supplied.
A local information-disclosure vulnerability in Microsoft Office Excel caused by use of an uninitialized resource.
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.