CVE-2026-88109 Microsoft Office Click-To-Run Elevation of Privilege Vulnerability
An authorized local attacker can exploit a use-after-free flaw in Microsoft Office Click-To-Run to elevate privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-88109?
CVE-2026-88109 is a high-severity use after free vulnerability in Microsoft 365 Apps, published on 13 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Use after free in Microsoft Office Click-To-Run allows an authorized attacker to elevate privileges locally.
Weakness: CWE-416
Which versions are affected by CVE-2026-88109?
It affects 3 products.
Products include Microsoft 365 Apps, Microsoft Office 2021, Microsoft Office 2024.
How do I fix CVE-2026-88109?
No fix has been published for CVE-2026-88109 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-88109 being exploited?
There is no known exploitation of CVE-2026-88109 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-qqr5-6qjq-ff6q.