Executive brief
Microsoft Outlook is the email and calendar client used by millions of enterprises and individuals worldwide. A heap buffer overflow vulnerability allows an attacker to send a specially crafted email that executes arbitrary code on a victim's computer without authentication or user interaction, potentially leading to complete system compromise and data theft.
Technical details
A heap-based buffer overflow exists in Microsoft Outlook's email message processing logic. The vulnerability is triggered when Outlook processes a maliciously crafted email attachment or message body, allowing an attacker to overwrite heap memory and execute arbitrary code. The attack is network-based and requires no authentication or user interaction beyond receiving the malicious email. Successful exploitation results in remote code execution with the privileges of the user running Outlook. Microsoft has released security patches to address this vulnerability.
Affected products
- Microsoft Outlook
Timeline
- 2026-09-08: disclosed