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CVE-2026-80091 Microsoft CVE debrief

Microsoft Office vulnerability CVE-2026-80091 allows unauthorized information disclosure over a network due to the use of an uninitialized resource. Defenders should assess exposure, prioritize remediation, and verify vulnerability status. This vulnerability affects Office 2016, 2019, 2021, and 2024 users, who should review Microsoft's patch advisory for specific guidance. The vulnerability has a medium severity and is caused by the use of an uninitialized resource in Microsoft Office, which could allow an attacker to disclose information.

Vendor
Microsoft
Product
Microsoft 365 Apps for Enterprise
CVSS
MEDIUM 6.5
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 and IT administrators responsible for Microsoft Office installations, particularly for Office 2016, 2019, 2021, and 2024 users, should assess exposure, prioritize remediation, and verify vulnerability status. They should review Microsoft's patch advisory for specific guidance and apply patches or updates as recommended.

Why it matters

CVE-2026-80091 is a medium-severity vulnerability in Microsoft Office that allows unauthorized information disclosure over a network. Defenders should assess exposure, prioritize remediation, and verify vulnerability status.

  • Verify vulnerability status of Office installations
  • Assess exposure and prioritize remediation
  • Apply patches or updates as recommended by Microsoft

Technical summary

CVE-2026-80091 is a medium-severity vulnerability in Microsoft Office caused by the use of an uninitialized resource, allowing unauthorized information disclosure over a network. The vulnerability affects Office 2016, 2019, 2021, and 2024 users. Defenders should assess exposure, prioritize remediation, and verify vulnerability status using Microsoft's patch advisory. The vulnerability has a CVSS score of 6.5 and is classified as medium severity.

Defensive priority

Medium priority for Office 2016, 2019, 2021, and 2024 users; verify vulnerability status and apply patches

Recommended defensive actions

  • Assess exposure of Office 2016, 2019, 2021, and 2024 installations
  • Verify vulnerability status using Microsoft's patch advisory
  • Apply patches or updates as recommended by Microsoft

Evidence notes

The CVE record and NVD entry provide details on the vulnerability. Microsoft has released a patch advisory. The vulnerability has been assessed as medium severity, with a CVSS score of 6.5. The CVE record was published on 2026-09-08T18:20:51.680Z and has not been modified since then. Defenders should verify the vulnerability status of Office installations and apply patches or updates as recommended by Microsoft.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-80091 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-80091

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

  • CVE-2026-80091 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-80091

    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.