CVE-2026-65807: Microsoft Excel Remote Code Execution Vulnerability
Access of resource using incompatible type ('type confusion') in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.
CSIRTS triage
- What
- Type confusion vulnerability allows unauthorized remote code execution through network-delivered files.
- Who is affected
- Users opening untrusted Excel documents from network sources or email.
- Urgency
- Critical severity; remote code execution over network without authentication is immediately exploitable and poses severe risk.
- Action
- Apply Microsoft security patches for CVE-2026-65807 immediately and avoid opening untrusted Excel files.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65807
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.
- Low exploitation riskCVE-2026-658070.43% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 36% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-65807 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- high[NEW] [high] Microsoft Office Products: Multiple Vulnerabilitiescert-bund
- unknownMultiple vulnerabilities in Microsoft Office (August 12, 2026)cert-fr-avis
- unknownNCSC-2026-0286 [1.00] [M/H] Vulnerabilities patched in Microsoft Officencsc-nl
- highCVE-2026-65807: Access of resource using incompatible type ('type confusion') in Microsoft Office Excel allows…nvd
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