Quick answers
- Is CVE-2026-78505 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-78505 being exploited in the wild.
- How severe is CVE-2026-78505?
- High severity, with a CVSS score of 8.8, published 8 September 2026.
- Which products and versions are affected?
- Microsoft Office.
- Is there a fix for CVE-2026-78505?
- 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-2026-78505 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-78505?
- Check whether you run Microsoft Office. 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 vulnerability exists in Microsoft Office that does not properly validate buffer boundaries during memory operations. The vulnerability can be triggered remotely when a user opens or processes a malicious Office document, without requiring authentication. An attacker can craft a specially formatted file that, when processed by Office, overflows a heap buffer and overwrites adjacent memory, achieving code execution with the privileges of the user running Office. A patch is expected from Microsoft through their regular security update cycle.
Affected products
- Microsoft Office
Timeline
- 2026-09-08: disclosed