CVE-2026-55133 in Office
Summary
by MITRE • 07/14/2026
Heap-based buffer overflow in Microsoft Office OneNote allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/15/2026
A heap-based buffer overflow vulnerability exists in Microsoft Office OneNote that enables unauthorized remote code execution attacks. This flaw resides within the memory management mechanisms of the application and specifically affects how OneNote processes certain data structures during document parsing operations. The vulnerability stems from inadequate bounds checking when handling user-supplied input within heap-allocated memory regions, creating opportunities for attackers to overwrite adjacent memory locations with malicious code payloads.
The technical implementation of this vulnerability involves the manipulation of structured data within OneNote documents that triggers improper memory allocation and subsequent buffer overflow conditions. When the application processes malformed or specially crafted content, it fails to validate the size of incoming data against allocated buffer boundaries, allowing attackers to write beyond intended memory limits. This condition typically occurs during parsing operations involving rich text formatting elements or embedded objects within note files.
From an operational perspective, this vulnerability represents a significant security risk as it enables local code execution without requiring elevated privileges. Attackers can exploit this weakness by crafting malicious OneNote documents that, when opened by an unsuspecting user, trigger the buffer overflow condition and subsequently execute arbitrary code within the context of the running application. The attack vector primarily involves social engineering tactics where users are诱导 to open compromised documents, making this vulnerability particularly dangerous in enterprise environments.
The impact extends beyond simple privilege escalation as this vulnerability can serve as a foothold for more extensive attacks within networked environments. Security researchers have identified this issue as aligning with CWE-121 heap-based buffer overflow patterns and can be mapped to ATT&CK technique T1059.001 for command and scripting interpreter execution. The vulnerability's exploitation potential increases when combined with other attack vectors, potentially enabling lateral movement and persistence mechanisms within compromised systems.
Organizations should implement immediate mitigations including applying Microsoft security patches as soon as they become available, implementing application whitelisting policies to restrict execution of untrusted Office documents, and deploying network monitoring solutions to detect suspicious file handling activities. Additionally, user education programs should emphasize the importance of verifying document sources before opening potentially malicious files. The vulnerability demonstrates the critical need for robust memory safety mechanisms in office productivity applications and highlights the importance of regular security updates to protect against emerging threats in Microsoft Office environments.