CVE-2026-55038 in Office
Summary
by MITRE • 07/14/2026
Stack-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/15/2026
A stack-based buffer overflow vulnerability exists in Microsoft Office Word that enables unauthorized attackers to execute arbitrary code locally on affected systems. This critical flaw occurs when the application fails to properly validate input data during processing of specially crafted documents, leading to memory corruption that can be exploited to gain control over the target system. The vulnerability stems from improper bounds checking mechanisms within the word processing engine, specifically when handling malformed or maliciously constructed document elements. Attackers can leverage this weakness by crafting malicious Office documents that trigger the overflow condition during normal document parsing operations, potentially allowing remote code execution with the privileges of the logged-in user.
The technical exploitation of this vulnerability follows a classic stack-based buffer overflow pattern where excessive data is written to a fixed-size buffer located on the program's stack memory region. When Word processes the malicious input without adequate bounds checking, it overflows the allocated stack space and corrupts adjacent memory locations including return addresses and function pointers. This memory corruption can be manipulated to redirect program execution flow to attacker-controlled code injected into the process memory. The vulnerability typically manifests when users open or preview malicious documents within the Word application, making it particularly dangerous in enterprise environments where document sharing is common.
The operational impact of this vulnerability extends beyond simple code execution as it provides attackers with persistent access to target systems and potentially enables further escalation within network environments. Successful exploitation can lead to complete system compromise, data exfiltration, and establishment of persistent backdoors. The vulnerability affects multiple versions of Microsoft Office Word across different operating systems, making it a widespread concern for organizations relying on Microsoft Office productivity suites. Security researchers have identified that the attack vector often involves social engineering tactics where users are tricked into opening malicious documents through email attachments or web downloads.
Organizations should implement immediate mitigations including applying the latest security patches from Microsoft and configuring application control measures to restrict document processing capabilities. The vulnerability aligns with CWE-121 stack-based buffer overflow classification and can be mapped to ATT&CK technique T1059 for command and scripting interpreter execution. Additional defensive measures include deploying email filtering solutions to block malicious attachments, implementing user education programs about phishing awareness, and configuring Microsoft Office to disable automatic document preview features. Network segmentation and privilege separation can help limit the potential damage from successful exploitation attempts. Regular security assessments and monitoring for anomalous process behaviors should be implemented to detect potential exploitation activities. The vulnerability demonstrates the critical importance of maintaining up-to-date software patches and implementing defense-in-depth strategies to protect against sophisticated attack vectors targeting common productivity applications.