CVE-2026-102858 in OneNote
Summary
by MITRE • 10/13/2026
Heap-based buffer overflow in Microsoft Office OneNote allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office OneNote application, specifically manifesting as a heap-based buffer overflow. This type of memory corruption error occurs when a program writes data beyond the allocated boundaries of a buffer located in the computer's random access memory, known as the heap. In the context of OneNote, this defect likely arises during the processing of specially crafted documents or embedded objects that trigger improper bounds checking within the application’s parsing routines. When an attacker constructs malicious input designed to exceed the expected size limits, it overwrites adjacent memory locations, potentially corrupting data structures such as function pointers or exception handlers. This corruption allows for arbitrary code execution with the privileges of the currently logged-in user, effectively granting the attacker full control over the affected system without requiring any additional authentication beyond opening the malicious file.
From a technical perspective, heap-based buffer overflows are particularly dangerous because they can be exploited to bypass modern memory protection mechanisms such as Data Execution Prevention and Address Space Layout Randomization if not properly mitigated by the application developer or operating system updates. The exploitation vector being network-accessible indicates that an attacker does not need physical access to the machine; instead, they can distribute malicious OneNote files via email attachments, shared drives, or web hosting services. When a victim opens these files, even without actively interacting with specific features beyond initial rendering, the vulnerable code path is triggered. This aligns closely with Common Weakness Enumeration identifier CWE-122, which defines heap-based buffer overflow as a weakness where data written to a heap region exceeds its allocated size. Furthermore, this vulnerability facilitates remote code execution scenarios often categorized under MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter subtechniques, allowing attackers to deploy malware, establish persistence, or move laterally within an enterprise network after initial compromise.
The operational impact of such a vulnerability is severe for both individual users and organizational IT infrastructure. For end-users, the immediate consequence is total system compromise, leading to potential data theft, installation of ransomware, or use of the machine as part of a botnet. For enterprises, this represents a significant risk vector because OneNote files are frequently shared across departments and external partners. An attacker leveraging this flaw could gain initial access to corporate networks through social engineering tactics involving malicious attachments. The lack of user interaction required for exploitation in some variants makes it particularly potent against automated scanning tools or targeted phishing campaigns where users might be tricked into opening seemingly legitimate documents.
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, which typically include patches that correct the memory management logic within OneNote to enforce strict buffer boundaries. Administrators should also consider implementing application control policies using tools like Windows Defender Application Control or AppLocker to restrict the execution of untrusted scripts and binaries, thereby limiting the impact if an exploit is successful. Additionally, enabling Protected View for files originating from the internet can prevent automatic code execution by opening documents in a sandboxed environment. Users must be educated on phishing awareness to avoid opening unsolicited attachments, while IT departments should ensure that email gateways are configured to scan and block malicious Office file types containing embedded scripts or macros. Regular vulnerability assessments and penetration testing focused on document parsing components can help identify similar weaknesses before they are exploited in the wild.