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PatchSiren cyber security CVE debrief

CVE-2026-81950 Microsoft CVE debrief

A double free vulnerability in Microsoft Office Excel allows an unauthorized attacker to execute code locally, with a CVSS score of 7.8 and HIGH severity. The CVE record was published on 2026-09-08T18:20:58.460Z and was last modified on 2026-09-17T20:18:41.153Z. The NVD entry is currently Analyzed. Defenders should assess exposure and prioritize patching, especially in environments where local access is not tightly controlled. This vulnerability requires verification of exposure and prompt patching to prevent exploitation.

Vendor
Microsoft
Product
Microsoft 365 Apps for Enterprise
CVSS
HIGH 7.8
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, especially in environments where local access is not tightly controlled, should assess exposure and prioritize patching.

Why it matters

A double free vulnerability in Microsoft Office Excel allows an unauthorized attacker to execute code locally, requiring defenders to verify exposure and prioritize patching.

  • Verify exposure of Microsoft Office Excel installations to prioritize patching.
  • Monitor for suspicious activity in Excel, especially in environments with high-risk users.
  • Apply patches from Microsoft as they become available to prevent exploitation.

Technical summary

A double free vulnerability in Microsoft Office Excel allows an unauthorized attacker to execute code locally. The vulnerability has a CVSS score of 7.8 and HIGH severity. It is crucial for defenders to verify exposure of Microsoft Office Excel installations, especially in environments where local access is not tightly controlled, and to review and apply patches from Microsoft as they become available.

Defensive priority

Defenders should prioritize verifying exposure of Microsoft Office Excel installations, especially in environments where local access is not tightly controlled.

Recommended defensive actions

  • Verify exposure of Microsoft Office Excel installations, especially in environments where local access is not tightly controlled.
  • Review and apply patches from Microsoft as they become available.
  • Monitor for suspicious activity in Excel, especially in environments with high-risk users.

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability, but do not specify which versions are affected or provide remediation guidance.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-81950 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-81950

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

  • CVE-2026-81950 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-81950

    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.