CVE-2026-58651 in Office
Summary
by MITRE • 08/11/2026
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 08/11/2026
A heap-based buffer overflow vulnerability exists in Microsoft Office Word that enables unauthorized attackers to achieve local code execution through carefully crafted malicious documents. This vulnerability stems from insufficient input validation and memory management practices within the word processing application when handling specially constructed data structures. The flaw occurs during the parsing of document elements where the application fails to properly bounds-check heap-allocated memory regions, allowing an attacker to overwrite adjacent memory locations with malicious code payloads.
The technical implementation of this vulnerability involves the exploitation of memory corruption mechanisms that leverage heap-based buffer overflows as defined by CWE-121. When a victim opens a specially crafted malicious document containing oversized or malformed data structures, the application's memory management routines fail to validate the input size before copying data into heap-allocated buffers. This allows attackers to overwrite critical memory pointers and function return addresses, ultimately enabling arbitrary code execution with the privileges of the compromised user account.
From an operational perspective, this vulnerability presents significant risk to enterprise environments where users frequently open documents from untrusted sources. The attack vector typically involves social engineering campaigns where malicious documents are delivered via email attachments or compromised websites, exploiting user trust to initiate the exploitation chain. The vulnerability affects multiple versions of Microsoft Office Word across different operating systems, making it particularly dangerous in diverse enterprise environments.
The impact of successful exploitation extends beyond simple code execution to potentially enable privilege escalation and persistent access within targeted systems. Attackers can leverage this vulnerability to install backdoors, exfiltrate sensitive data, or establish command and control channels. This aligns with ATT&CK technique T1059.007 for command and script interpreter and T1068 for exploit for privilege escalation. Organizations should implement comprehensive security measures including regular patch management, user education programs, email filtering solutions, and application whitelisting policies to mitigate the risk associated with this vulnerability.
Microsoft has addressed this vulnerability through security updates that include improved input validation mechanisms and enhanced memory protection features such as stack canaries and address space layout randomization. System administrators should prioritize immediate deployment of these patches while maintaining layered defense strategies including network segmentation, endpoint detection and response solutions, and regular security assessments to identify potential exploitation attempts. The vulnerability demonstrates the critical importance of proper memory management practices in preventing heap-based buffer overflow exploits that continue to represent a significant threat vector in modern cybersecurity landscapes.