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CVE-2026-58618 Microsoft CVE debrief

A high-severity vulnerability, CVE-2026-58618, was found in Microsoft Office Excel. This heap-based buffer overflow vulnerability allows an unauthorized attacker to execute code locally. The CVE record was published on 2026-07-14T17:17:13.587Z and has not been modified since then. The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. Multiple CPE criteria are listed, including Microsoft 365 Apps, Excel, Office 2019, Office 2021, and Office 2024, across various platforms. Security teams should prioritize patching this vulnerability to prevent local code execution. The vulnerability requires user interaction (UI:R) and has high impacts on confidentiality, integrity, and availability (C:H/I:H/A:H).

Vendor
Microsoft
Product
Microsoft 365 Apps for Enterprise
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-14
Original CVE updated
2026-07-16
Advisory published
2026-07-14
Advisory updated
2026-07-16

Who should care

Security teams and administrators responsible for Microsoft Office Excel installations should prioritize patching this vulnerability to prevent local code execution. This includes teams managing Microsoft 365 Apps, Excel, Office 2019, Office 2021, and Office 2024 across various platforms. Vulnerability management and security teams should review and verify patch deployment.

Technical summary

CVE-2026-58618 is a heap-based buffer overflow vulnerability in Microsoft Office Excel. The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. The CVSS vector is CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Multiple CPE criteria are listed, including Microsoft 365 Apps, Excel, Office 2019, Office 2021, and Office 2024, across various platforms.

Defensive priority

High priority should be given to patching CVE-2026-58618 due to its high severity and potential for local code execution.

Recommended defensive actions

  • Apply patches from Microsoft for CVE-2026-58618
  • Inventory and update vulnerable Microsoft Office Excel installations
  • Implement compensating controls, such as monitoring for suspicious activity
  • Review and verify patch deployment in managed environments
  • Monitor relevant logs for exposed assets that need extra review

Evidence notes

The CVE record and NVD detail provide information on the vulnerability. Microsoft has provided a patch and vendor advisory for CVE-2026-58618. The vulnerability is a heap-based buffer overflow in Microsoft Office Excel, allowing an unauthorized attacker to execute code locally. Evidence is limited to CVE and NVD details. Defenders should verify patch deployment, review vendor advisories, and monitor for suspicious activity related to Excel. The CVE was published on 2026-07-14T17:17:13.587Z. No additional information is available on affected scope or vendor guidance beyond official sources.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-58618 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-58618

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

  • CVE-2026-58618 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-58618

    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.