CVE-2026-78515 Microsoft CVE debrief

Who should care

Defenders responsible for Microsoft Office deployments, particularly those using Excel, should assess exposure and prioritize patching. This includes IT administrators, security teams, and operators managing Microsoft Office environments. They should verify their inventory and implement necessary mitigations to prevent potential information disclosure.

Why it matters

CVE-2026-78515 is a Medium-severity vulnerability in Microsoft Office Excel that allows out-of-bounds reads, potentially leading to information disclosure. Defenders should prioritize patching affected systems and verify their inventory to mitigate potential risks.

• Potential information disclosure over the network
• Requires verification of affected versions and systems
• Patching and inventory management are crucial for mitigation

Technical summary

CVE-2026-78515 is an out-of-bounds read vulnerability in Microsoft Office Excel, allowing unauthorized attackers to disclose information over a network. The vulnerability has a CVSS score of 6.5 and is classified as Medium severity. Affected systems should be patched or mitigated to prevent potential information disclosure. The vulnerability's technical details indicate a need for defenders to prioritize patching and verify affected systems.

Defensive priority

Medium-priority patching and verification recommended for affected Microsoft Office deployments.

Recommended defensive actions

• Apply patches for affected Microsoft Office versions
• Verify and inventory affected systems
• Monitor for potential information disclosure attempts

Evidence notes

The CVE record and NVD entry provide details on the vulnerability. Specific version information and exploitation details are not provided. Defenders should verify their inventory and assess exposure to mitigate potential risks. The CVE Program and NVD offer official guidance on this vulnerability.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.