Quick answers
- Is CVE-2026-81397 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-81397 being exploited in the wild.
- How severe is CVE-2026-81397?
- High severity, with a CVSS score of 7.8, published 8 September 2026.
- Which products and versions are affected?
- Microsoft Excel.
- Is there a fix for CVE-2026-81397?
- 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-2026-81397 attacked?
- It is attacked with local access.
- Am I affected by CVE-2026-81397?
- Check whether you run Microsoft 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
A heap-based buffer overflow exists in Microsoft Excel's file parsing logic. The vulnerability is triggered when Excel processes a specially crafted spreadsheet file, causing a buffer overrun in the heap memory region. An attacker can exploit this by sending or hosting a malicious Excel file that, when opened by a user, executes arbitrary code with the privileges of the user running Excel. No special privileges or prior authentication are required; user interaction (opening the file) is the only precondition. The attack vector is local execution via file handling.
Affected products
- Microsoft Excel
Timeline
- 2026-09-08: disclosed