CVE-2026-78506 Microsoft Office Word Information Disclosure Vulnerability
An attacker can disclose local information via improper null termination in Microsoft Office Word, requiring a patch for mitigation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-78506?
CVE-2026-78506 is a medium-severity vulnerability in Microsoft 365 Apps, published on 8 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Improper null termination in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
Weakness: CWE-170
Which versions are affected by CVE-2026-78506?
It affects 6 products.
Products include Microsoft 365 Apps, Microsoft Microsoft 365, Microsoft Office 2019, Microsoft Office 2021, Microsoft Office 2024, Microsoft Word.
How do I fix CVE-2026-78506?
No fix has been published for CVE-2026-78506 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-78506 being exploited?
There is no known exploitation of CVE-2026-78506 in the wild and no public exploit code.
Other vulnerabilities in Microsoft 365 Apps
- CVE-2024-21413 Microsoft Outlook Improper Input Validation
- CVE-2023-23397 Microsoft Office Outlook Privilege Escalation
- CVE-2024-38189 Microsoft Project Remote Code Execution Vulnerability
- CVE-2023-35311 Microsoft Outlook Security Feature Bypass
- CVE-2026-21514 Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision
Sources
Also known as GHSA-c99c-vfp3-j237.