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PatchSiren cyber security CVE debrief

CVE-2026-55948 Microsoft CVE debrief

CVE-2026-55948 is a high-severity vulnerability in Microsoft Office Excel, allowing unauthorized attackers to execute code locally. The vulnerability has a CVSS score of 7.8 and is classified as HIGH. It was published on 2026-07-14T17:17:09.637Z and last modified on 2026-07-16T11:50:22.550Z. This use-after-free issue in Microsoft Office Excel can be exploited by attackers to gain local code execution, posing a significant risk to users, particularly in enterprise environments.

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

Users of Microsoft Office Excel, particularly those in enterprise environments, should be aware of this vulnerability and take necessary precautions to mitigate the risk. This includes IT administrators, security teams, and operators who manage Microsoft Office deployments.

Technical summary

The vulnerability is a use-after-free issue in Microsoft Office Excel, which allows an unauthorized attacker to execute code locally. The CVSS vector is CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, indicating a high severity vulnerability. This issue arises from the improper handling of memory in Microsoft Office Excel, enabling attackers to execute arbitrary code.

Defensive priority

High

Recommended defensive actions

  • Apply the patch provided by Microsoft
  • Ensure that Microsoft Office Excel is up-to-date
  • Implement compensating controls, such as monitoring and exception tracking
  • Conduct regular inventory checks to ensure that all affected systems are patched
  • Review and update security configurations to prevent exploitation

Evidence notes

The CVE record was published on 2026-07-14T17:17:09.637Z and last modified on 2026-07-16T11:50:22.550Z. The NVD entry is currently Analyzed. The vulnerability affects multiple versions of Microsoft Office, including Office 2016, Office 2019, Office 2021, and Office 2024. There is limited information available about the specific details of the vulnerability, and defenders should verify the affected scope and severity with the vendor.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-55948 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-55948

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

  • CVE-2026-55948 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-55948

    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.