CVE-2026-65664
Summary
by MITRE • 08/11/2026
Heap-based buffer overflow in Microsoft Office 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 within Microsoft Office applications that enables remote code execution by unauthorized attackers who have already gained local system access. This flaw resides in the memory management handling of office document processing functions, specifically when parsing malformed or specially crafted input data structures. The vulnerability stems from insufficient bounds checking during heap allocation operations where attacker-controlled data can overwrite adjacent memory regions, potentially corrupting program execution flow and allowing arbitrary code execution with the privileges of the targeted user.
The technical mechanism involves improper validation of input parameters within Microsoft Office's document parser components, particularly affecting word processing and spreadsheet applications. When these applications encounter malformed file structures or maliciously crafted content during document loading or rendering processes, the heap memory allocation routines fail to properly verify data boundaries before copying or storing information. This weakness creates opportunities for attackers to manipulate heap metadata and overwrite critical program variables or function pointers, effectively redirecting execution flow to malicious code injected into the process memory space.
From an operational perspective this vulnerability represents a significant security risk as it requires minimal privileges for exploitation since local system access is already assumed by the attacker. The attack vector typically involves social engineering techniques to deliver malicious office documents to target users who then open them, triggering the vulnerable parsing routines. Once executed, the malicious code can establish persistence mechanisms, escalate privileges if necessary, and potentially exfiltrate sensitive data or establish command and control channels. The impact extends beyond individual system compromise to potential lateral movement within network environments where Microsoft Office applications are commonly used.
Security professionals should implement multiple layers of defense including regular patch management programs that address known vulnerabilities in Microsoft Office applications, application whitelisting policies that restrict execution of unsigned code, and enhanced monitoring for suspicious process behaviors or memory access patterns. Network segmentation and user privilege reduction practices can limit the potential damage from successful exploitation attempts. Organizations must also maintain current threat intelligence feeds to identify emerging attack patterns targeting similar vulnerabilities and implement robust incident response procedures that include forensic analysis capabilities to detect and contain compromised systems. The vulnerability aligns with CWE-122 heap-based buffer overflow classifications and maps to attack techniques described in the MITRE ATT&CK framework under process injection and privilege escalation domains, emphasizing the need for comprehensive security controls beyond traditional perimeter defenses.