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CVE-2026-55042 Microsoft CVE debrief

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-14T18:18:15.730Z and has not been modified since then. The NVD entry is currently Analyzed. This vulnerability, CVE-2026-55042, involves the use of an uninitialized resource in Microsoft Office, which could allow an unauthorized attacker to disclose information locally. The vulnerability has a CVSS score of 5.5 and is classified as MEDIUM severity. It affects various versions of Microsoft Office, including Office 2016, 2019, 2021, and 2024, across different platforms. Users of Microsoft Office 2016, 2019, 2021, and 2024, including enterprise and LTS versions for Windows and macOS, should prioritize patching to mitigate the risk of local information disclosure. The CVE record and NVD details indicate a MEDIUM severity vulnerability in Microsoft Office due to the use of an uninitialized resource. Affected products include Microsoft 365 Apps, Office 2016, 2019, 2021, and 2024, across various platforms. Microsoft has provided a patch for this vulnerability. To address this vulnerability, it is essential to apply the official patch from Microsoft as soon as possible, inventory and verify the presence of affected Microsoft Office versions, implement compensating controls such as monitoring for suspicious activity, and consider exception tracking for systems that cannot be immediately patched.

Vendor
Microsoft
Product
Microsoft 365 Apps for Enterprise
CVSS
MEDIUM 5.5
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 2016, 2019, 2021, and 2024, including enterprise and LTS versions for Windows and macOS, should prioritize patching to mitigate the risk of local information disclosure.

Technical summary

The CVE-2026-55042 vulnerability involves the use of an uninitialized resource in Microsoft Office, which could allow an unauthorized attacker to disclose information locally. The vulnerability has a CVSS score of 5.5 and is classified as MEDIUM severity. It affects various versions of Microsoft Office, including Office 2016, 2019, 2021, and 2024, across different platforms.

Defensive priority

Medium priority should be given to patching this vulnerability, as it could lead to local information disclosure.

Recommended defensive actions

  • Apply the official patch from Microsoft as soon as possible.
  • Inventory and verify the presence of affected Microsoft Office versions.
  • Implement compensating controls, such as monitoring for suspicious activity.
  • Consider exception tracking for systems that cannot be immediately patched.

Evidence notes

The CVE record and NVD details indicate a MEDIUM severity vulnerability in Microsoft Office due to the use of an uninitialized resource. Affected products include Microsoft 365 Apps, Office 2016, 2019, 2021, and 2024, across various platforms. Microsoft has provided a patch for this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-55042 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-55042

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

  • CVE-2026-55042 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-55042

    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.