# CVE-2026-124178: Microsoft Office Excel out-of-bounds read

Source: https://junglewise.ai/threats/cve-2026-124178-out-of-bounds-read-in-microsoft-office-excel-allows-an  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-124178 · Severity: medium · CVSS 6.5 · Published 2026-11-10

Microsoft Office Excel contains an out-of-bounds read vulnerability that allows an attacker to read sensitive information from a computer via a network. An attacker can exploit this by sending a malicious Excel file to a user, potentially exposing confidential business data or personal information without authorization.

Technologies: [Microsoft Office Excel](https://junglewise.ai/threats/technologies/office-excel). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-124178 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-124178 being exploited in the wild.

**How severe is CVE-2026-124178?** Medium severity, with a CVSS score of 6.5, published 10 November 2026.

**Which products and versions are affected?** Microsoft Office Excel.

**Is there a fix for CVE-2026-124178?** 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-2026-124178 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-124178?** Check whether you run Microsoft Office Excel. 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

An out-of-bounds read in Microsoft Office Excel permits information disclosure when processing specially crafted Excel files. The vulnerability can be triggered over the network and results in the exposure of memory contents that may contain sensitive data; no user interaction or authentication is required beyond opening a malicious file.

## Affected products

- Microsoft Office Excel

## Timeline

- 2026-11-10: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-124178](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-124178)

## Related threats

- [Microsoft Office Excel unsafe deserialization in file parsing](https://junglewise.ai/threats/cve-2026-124229-deserialization-of-untrusted-data-in-microsoft-office-excel)
- [Microsoft Office Excel use-after-free remote code execution](https://junglewise.ai/threats/cve-2026-124187-use-after-free-in-microsoft-office-excel-allows-an-unauthorized)
- [Microsoft Office Excel buffer over-read information disclosure](https://junglewise.ai/threats/cve-2026-124183-buffer-over-read-in-microsoft-office-excel-allows-an)
- [Microsoft Office Excel out-of-bounds read information disclosure](https://junglewise.ai/threats/cve-2026-124179-out-of-bounds-read-in-microsoft-office-excel-allows-an)
- [Microsoft Office Excel heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-124176-heap-based-buffer-overflow-in-microsoft-office-excel-allows-an)