CVE-2026-97781 in OneNote
Summary
by MITRE • 10/15/2026
Improper neutralization of special elements used in a command ('command injection') in Microsoft Office OneNote 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 Microsoft Office OneNote, specifically categorized under the Common Weakness Enumeration (CWE) as CWE-78: Improper Neutralization of Special Elements used in an Operating System Command, commonly known as command injection. This type of vulnerability arises when software constructs operating system commands using externally influenced input without sufficiently neutralizing special elements that could alter the intended command structure. In the context of OneNote, this flaw allows an attacker to inject malicious shell commands into data processed by the application, leading to arbitrary code execution on the victim's machine. The severity is amplified because the attack vector involves network-based exploitation, meaning a remote, unauthenticated attacker can trigger the vulnerability simply by convincing a user to open a specially crafted file or link associated with OneNote content.
From an operational perspective, this flaw represents a significant risk to organizational security postures and individual privacy. When successful, command injection in OneNote does not merely result in data leakage; it grants the attacker full control over the affected system under the context of the currently logged-in user. This can lead to the installation of malware, creation of backdoors for persistent access, exfiltration of sensitive documents stored within or linked from OneNote notebooks, and lateral movement across a network if the compromised machine serves as an entry point. The ability to execute code over a network makes this vulnerability particularly dangerous in enterprise environments where users frequently collaborate on shared notebooks accessed via cloud services like Microsoft 365, increasing the surface area for potential attacks through phishing campaigns or maliciously hosted web content that triggers OneNote processing routines.
The technical mechanism typically involves manipulating how OneNote parses specific file formats or embedded objects within a notebook. If the application fails to properly sanitize inputs before passing them to underlying system commands—such as those used for rendering, converting, or interacting with external resources—an attacker can craft payloads that break out of the intended sandboxed environment. For instance, by injecting characters like semicolons, pipes, or ampersands into a field expected to contain only safe text data, an attacker can chain multiple system commands together. This allows them to execute arbitrary binaries, scripts, or PowerShell code on the host operating system. The impact is consistent with ATT&CK technique T1059: Command and Scripting Interpreter, where adversaries use built-in OS utilities to perform actions that facilitate further compromise of the target environment.
Mitigation strategies must focus on both immediate remediation and long-term defensive posture improvements. Organizations should immediately apply the latest security updates provided by Microsoft for Office OneNote, as these patches typically include code changes that enforce stricter input validation and output encoding practices. Administrators should also consider implementing application control policies to restrict the execution of unauthorized scripts or binaries from temporary directories where downloaded malicious files often reside. Furthermore, user awareness training is crucial; since many command injection vulnerabilities require social engineering elements such as opening a specific file, educating users on recognizing suspicious attachments and links can significantly reduce the likelihood of successful exploitation. Enabling macro security settings to disable all macros without notification and leveraging Microsoft Defender for Office 365 to block malicious files before they reach end-users are additional layers of defense that complement patching efforts in mitigating this risk.