CVE-2026-97012 in Office
Summary
by MITRE • 10/15/2026
Stack-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office Outlook application, specifically manifesting as a stack-based buffer overflow condition that can be exploited remotely via network connections. This type of vulnerability arises when the software fails to properly validate the length or boundaries of user-supplied input before copying it into a fixed-size buffer located on the call stack. In the context of an email client like Outlook, this often occurs during the parsing and rendering of maliciously crafted messages, attachments, or embedded objects such as HTML content, ActiveX controls, or specific file formats processed by the application's internal parsers. When an attacker sends a specially constructed message containing data that exceeds the allocated buffer size, the excess data overwrites adjacent memory locations on the stack, potentially including critical control structures like return addresses and saved frame pointers.
From a technical perspective, this flaw aligns with Common Weakness Enumeration (CWE) identifier CWE-121, which describes Stack-based Buffer Overflow. The exploitation mechanism typically involves an attacker crafting a payload that not only overflows the buffer but also injects shellcode or redirects execution flow to existing code within the application process space, known as Return-Oriented Programming (ROP). By manipulating the stack pointer and return address, the attacker can hijack the control flow of the Outlook process. This allows for arbitrary code execution with the privileges of the currently logged-in user. The vulnerability is particularly severe because it enables remote code execution without requiring any physical interaction or prior authentication beyond receiving a malicious email, provided that certain conditions such as preview pane viewing or automatic message processing are enabled in the client configuration.
The operational impact of this vulnerability is profound, affecting both individual users and enterprise environments relying on Microsoft Outlook for communication. Successful exploitation grants an unauthorized attacker full control over the affected system, enabling them to install programs, view, change, or delete data, and create new accounts with full user rights. In a corporate setting, this can serve as an initial access vector for broader network compromises, allowing attackers to pivot laterally across systems using stolen credentials harvested from the compromised machine. The ability to execute code over a network means that the attack surface is significantly expanded, as any system running a vulnerable version of Outlook and connected to the internet or internal networks with email traffic becomes a potential target. This aligns with MITRE ATT&CK techniques such as T1566.001 Spearphishing Attachment and T1203 Exploitation for Client Execution, highlighting how social engineering combined with technical exploitation facilitates unauthorized access.
Mitigation strategies must focus on both immediate remediation and long-term defensive posture improvements. The primary defense is the prompt application of security patches released by Microsoft to address this specific buffer overflow issue in all affected versions of Outlook. Organizations should prioritize patch management processes to ensure that updates are deployed rapidly across all endpoints. Additionally, implementing strict email filtering policies at the gateway level can help block malicious payloads before they reach user mailboxes. Security awareness training for employees is crucial to prevent them from opening suspicious attachments or clicking on links in unsolicited emails. Furthermore, enabling Protected View and disabling automatic preview of messages with potentially dangerous content can reduce the attack surface by preventing the rendering engine from processing untrusted data until explicitly approved by the user. Network segmentation and endpoint detection and response (EDR) solutions should also be utilized to monitor for anomalous behavior indicative of exploitation attempts, such as unexpected process creation or memory access violations within Outlook processes.