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CVE-2026-55949: Microsoft Excel Remote Code Execution Vulnerability

highCVSS 7.8CVE-2026-55949
Use of uninitialized resource in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

CSIRTS triage

vendor: Microsoftproduct: ExcelRemote code execution
What
An unauthorized attacker can execute code locally due to the use of uninitialized resources.
Who is affected
Deployments of Microsoft Excel are affected.
Urgency
Remediation is important due to high severity and potential for remote code execution.
Action
Apply the latest security patch for Microsoft Excel.

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Details

Source
Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity
high — CVSS 7.8
Published
2026-07-14
Exploitation
Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55949

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-55949coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

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