CVE-2026-68801

This heap-based buffer overflow in Excel's binary format parsing carries a CVSS 7.8 that treats the vulnerability as a contained local execution issue. In practice, this classification fundamentally misrepresents the real-world threat. The attack path is straightforward and well-established: a malicious .xlsx arrives via email phishing, the victim opens it, and the overflow executes with the victim's full local privileges. In enterprise environments, those privileges typically map directly to Active Directory credentials, meaning the 'contained' local execution immediately becomes domain-wide credential theft and lateral movement. The blast radius of 'one workstation' assumed by CVSS is fiction in any organization using Office connected to corporate identity systems. Beyond the immediate misclassification, this vulnerability represents another instance in a decades-long genetic sequence. The heap overflow exists in legacy .xls parsing code maintained for backward compatibility — code that has effectively been abandoned in active development but never received updated threat modeling. The engineers who understood why document parsers needed sandboxing have cycled out; the institutional knowledge that 'document-based overflows become remote execution through phishing' exists in vulnerability reports but never gets re-ingested into the threat model for the codebase being maintained. The EPSS score of 0.00332 reflects the point-in-time probability of exploitation but ignores the temporal dimension: disclosed Office vulnerabilities become infrastructure for the threat community, chained with macro execution and other primitives. Each day after disclosure, the practical exploit probability compounds as attack playbooks integrate the new vulnerability. Prioritize these as perimeter-adjacent vulnerabilities regardless of the 'local' CVSS label. Treat any unpatched Office instance as credential exposure until remediated. The scoring framework hasn't caught up to this reality — your defense posture must.

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