PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-81389 Microsoft CVE debrief

A heap-based buffer overflow vulnerability exists in Microsoft Office Excel, which could allow an unauthorized attacker to execute code locally. The CVE record was published on 2026-09-08T18:20:55.243Z and has not been modified since then. The NVD entry is currently Analyzed. Defenders responsible for Microsoft Office Excel installations should assess exposure and prioritize patching to prevent potential local code execution. The vulnerability has a CVSS score of 7 and a severity of HIGH, indicating a significant risk. However, the CVE record and NVD detail page do not specify versions or provide remediation details, limiting the ability to assess the full scope of the ...

Vendor
Microsoft
Product
Microsoft 365 Apps for Enterprise
CVSS
HIGH 7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-08
Original CVE updated
2026-09-17
Advisory published
2026-09-08
Advisory updated
2026-09-17

Who should care

Defenders responsible for Microsoft Office Excel installations should assess exposure and prioritize patching to prevent potential local code execution.

Why it matters

Defenders should prioritize patching vulnerable Microsoft Office Excel installations to prevent potential local code execution. The vulnerability has a CVSS score of 7 and a severity of HIGH, indicating a significant risk. However, the CVE record and NVD detail page do not specify versions or provide remediation details, limiting the ability to assess the full scope of the vulnerability.

  • Potential local code execution
  • Need to patch vulnerable Microsoft Office Excel installations
  • Inventory and assess exposure of Microsoft Office Excel installations
  • Monitor for potential exploitation attempts

Technical summary

A heap-based buffer overflow vulnerability exists in Microsoft Office Excel, which could allow an unauthorized attacker to execute code locally. The vulnerability has a CVSS score of 7 and a severity of HIGH. The CVE record was published on 2026-09-08T18:20:55.243Z and has not been modified since then. The NVD entry is currently Analyzed. Defenders responsible for Microsoft Office Excel installations should assess exposure and prioritize patching to prevent potential local code execution. The vulnerability is ...

Defensive priority

Defenders should prioritize patching vulnerable Microsoft Office Excel installations to prevent potential local code execution.

Recommended defensive actions

  • Patch vulnerable Microsoft Office Excel installations
  • Inventory and assess exposure of Microsoft Office Excel installations
  • Monitor for potential exploitation attempts

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability, but do not specify versions or provide remediation details. The NVD entry is currently Analyzed. The CVE record was published on 2026-09-08T18:20:55.243Z and has not been modified since then. The vulnerability has a CVSS score of 7 and a severity of HIGH. Defenders should prioritize patching vulnerable Microsoft Office Excel installations to prevent potential local code execution. However, the CVE record and N

Sources and references

Verified primary and authoritative sources

  • CVE-2026-81389 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-81389

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-81389 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-81389

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental 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.