# CVE-2026-55042: Microsoft Office information disclosure via uninitialized resource

Source: https://junglewise.ai/threats/cve-2026-55042-microsoft-office-information-disclosure-via-uninitialized  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-14. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

CVE-2026-55042 · Severity: medium · CVSS 5.5 · Published 2026-07-14

A security vulnerability in Microsoft Office could allow an attacker to access sensitive information on a user's computer. To exploit this, an attacker would typically need to convince a user to open a specially crafted file. This could lead to the unauthorized disclosure of private data stored in the system's memory.

Technologies: [Microsoft 365 Apps for Enterprise](https://junglewise.ai/threats/technologies/365-apps-for-enterprise), [Microsoft Office 2016](https://junglewise.ai/threats/technologies/office-2016), [Microsoft Office 2019](https://junglewise.ai/threats/technologies/office-2019), [Microsoft Office 365 for Mac](https://junglewise.ai/threats/technologies/office-365-for-mac), [Microsoft Office LTSC 2021](https://junglewise.ai/threats/technologies/office-ltsc-2021), [Microsoft Office LTSC 2024](https://junglewise.ai/threats/technologies/office-ltsc-2024), [Microsoft Office LTSC for Mac 2021](https://junglewise.ai/threats/technologies/office-ltsc-for-mac-2021), [Microsoft Office LTSC for Mac 2024](https://junglewise.ai/threats/technologies/office-ltsc-for-mac-2024). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-55042 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55042 being exploited in the wild.

**How severe is CVE-2026-55042?** Medium severity, with a CVSS score of 5.5, published 14 July 2026.

**Which products and versions are affected?** Microsoft 365 Apps for Enterprise 16.0.1 and later versions prior to security updates; Microsoft Office 2016 16.0.0 to 16.0.5561.1000; Microsoft Office 2019 19.0.0 and later versions prior to security updates; Microsoft Office 365 for Mac 1.0.0 to 16.111.26071215; and 4 more.

**Is there a fix for CVE-2026-55042?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-55042 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-55042?** Check whether you run Microsoft 365 Apps for Enterprise, Microsoft Office 2016, Microsoft Office 2019 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability classified as CWE-908 (Use of Uninitialized Resource) exists in multiple versions of Microsoft Office, including Office 2016, 2019, LTSC, and Microsoft 365 Apps. The flaw allows a local attacker to disclose sensitive information by leveraging uninitialized memory resources. Exploitation requires user interaction, typically involving the victim opening a malicious file. Successful exploitation results in a high impact on confidentiality but does not affect integrity or availability. Microsoft has released security updates to address this issue across affected platforms.

## Affected products

- Microsoft Microsoft 365 Apps for Enterprise 16.0.1 and later versions prior to security updates
- Microsoft Microsoft Office 2016 16.0.0 to 16.0.5561.1000
- Microsoft Microsoft Office 2019 19.0.0 and later versions prior to security updates
- Microsoft Microsoft Office 365 for Mac 1.0.0 to 16.111.26071215
- Microsoft Microsoft Office LTSC 2021 16.0.1 and later versions prior to security updates
- Microsoft Microsoft Office LTSC 2024 16.0.0 and later versions prior to security updates
- Microsoft Microsoft Office LTSC for Mac 2021 16.0.1 to 16.111.26071215
- Microsoft Microsoft Office LTSC for Mac 2024 16.0.0 to 16.111.26071215

## Timeline

- 2026-07-14: disclosed
- 2026-07-14: advisory

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55042](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55042)

## Related threats

- [Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information locally.](https://junglewise.ai/threats/cve-2026-70310-out-of-bounds-read-in-microsoft-office-word-allows-an)
- [Microsoft Office out-of-bounds read information disclosure](https://junglewise.ai/threats/cve-2026-56195-microsoft-office-out-of-bounds-read-information-disclosure)
- [Microsoft Office Out-of-bounds Read Information Disclosure](https://junglewise.ai/threats/cve-2026-56192-microsoft-office-out-of-bounds-read-information-disclosure)
- [Microsoft Office Excel heap buffer overflow](https://junglewise.ai/threats/cve-2026-56156-microsoft-office-excel-heap-buffer-overflow)
- [Microsoft Excel use of uninitialized resource code execution](https://junglewise.ai/threats/cve-2026-55949-microsoft-excel-use-of-uninitialized-resource-code-execution)