CVE-2026-26109 Microsoft Excel Remote Code Execution Vulnerability
An out-of-bounds read in Microsoft Excel allows attackers to execute code locally, requiring users to apply vendor patches.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-26109?
CVE-2026-26109 is a high-severity memory corruption vulnerability in Microsoft 365 Apps, published on 10 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
Weakness: CWE-125
Which versions are affected by CVE-2026-26109?
It affects 5 products.
Products include Microsoft 365 Apps, Microsoft Excel, Microsoft Office, Microsoft Office Long Term Servicing Channel, Microsoft Office Online Server.
How do I fix CVE-2026-26109?
No fix has been published for CVE-2026-26109 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-26109 being exploited?
There is no known exploitation of CVE-2026-26109 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-xfqf-gmc6-gw8v.