Quick answers
- Is CVE-2026-78517 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-78517 being exploited in the wild.
- How severe is CVE-2026-78517?
- High severity, with a CVSS score of 8.8, published 8 September 2026.
- Which products and versions are affected?
- Microsoft Office Word.
- Is there a fix for CVE-2026-78517?
- 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-2026-78517 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-78517?
- Check whether you run Microsoft Office Word. 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 Office Word due to improper input validation when processing crafted document files. The vulnerability can be triggered by opening a specially malformed Word document, and does not require authentication or user privileges beyond the ability to open the file. An attacker can exploit this to achieve arbitrary code execution in the context of the user running Office. The attack vector is primarily network-based (delivery via email or web download), and successful exploitation provides the attacker with full execution capability on the affected system.
Affected products
- Microsoft Office Word
Timeline
- 2026-09-08: disclosed