Quick answers
- Is CVE-2026-78518 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-78518 being exploited in the wild.
- How severe is CVE-2026-78518?
- High severity, with a CVSS score of 8.8, published 8 September 2026.
- Which products and versions are affected?
- Microsoft Office Excel.
- Is there a fix for CVE-2026-78518?
- 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-2026-78518 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-78518?
- 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 vulnerability exists in Microsoft Office Excel's file parsing logic. The vulnerability is triggered when Excel processes specially crafted spreadsheet files, causing the application to read memory beyond intended boundaries. This can be exploited remotely by delivering a malicious Excel file to a user; no authentication or user interaction beyond opening the file is required. A successful exploit allows remote code execution with the privileges of the user running Excel. Microsoft has released patches to address this vulnerability.
Affected products
- Microsoft Office Excel
Timeline
- 2026-09-08: disclosed