CVE-2026-64920 in Access
Summary
by MITRE • 08/11/2026
Heap-based buffer overflow in Microsoft Office Access allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 08/12/2026
A heap-based buffer overflow vulnerability exists within Microsoft Office Access that enables unauthorized attackers to achieve local code execution. This vulnerability stems from insufficient input validation and memory management practices when processing specially crafted malicious files or data structures within the application. The flaw occurs in the heap memory allocation routines where the application fails to properly bounds-check data before copying it into allocated memory buffers, creating opportunities for attackers to overwrite adjacent memory locations with malicious code payloads.
The technical implementation of this vulnerability involves the exploitation of memory corruption patterns that allow attackers to manipulate heap metadata and control execution flow. When Office Access processes malformed input through its database engine or file parsing components, the application allocates heap memory without adequate boundary checks, enabling buffer overflows that can be leveraged for arbitrary code execution. This type of vulnerability aligns with CWE-121 heap-based buffer overflow classification and represents a critical security weakness in Microsoft's office suite applications.
The operational impact of this vulnerability extends beyond simple privilege escalation scenarios as it provides attackers with persistent local access to compromised systems. Once successfully exploited, the attacker can execute malicious code with the privileges of the targeted user account, potentially leading to full system compromise through subsequent lateral movement or privilege escalation techniques. The vulnerability is particularly concerning because Office Access applications are commonly used in enterprise environments where users may have elevated permissions and sensitive data access.
Security professionals should implement immediate mitigations including applying Microsoft security patches and updates as soon as they become available through official channels. Network segmentation and user access controls can help limit the potential impact of successful exploitation attempts. Additionally, implementing application whitelisting policies that restrict execution of unauthorized Office applications can provide defense-in-depth protection against this vulnerability. Organizations should also consider monitoring for suspicious file processing activities and unusual memory allocation patterns that may indicate exploitation attempts.
From an ATT&CK framework perspective, this vulnerability maps to multiple techniques including privilege escalation through code injection and execution of malicious payloads with system-level privileges. The attack chain typically involves initial access through phishing campaigns delivering malicious Office documents that trigger the buffer overflow condition during normal application operation. Security teams should monitor for indicators such as unusual process creation patterns, memory corruption artifacts, and suspicious file execution behaviors that may suggest exploitation attempts.
Microsoft has addressed this vulnerability through security updates that include improved input validation routines and enhanced heap memory management practices within Office Access applications. Organizations should prioritize patch management processes to ensure all systems receive these critical security updates promptly. Regular security assessments of Office application usage patterns and user behavior analytics can help identify potential exploitation attempts before they result in successful compromise of enterprise systems.
The remediation strategy should incorporate multiple layers of protection including endpoint detection and response solutions that monitor for heap-based memory corruption indicators, regular vulnerability scanning of Office environments, and comprehensive user education about the risks of opening untrusted Office documents. System administrators should also implement strict access controls and audit logging to track Office application usage patterns that may indicate attempted exploitation of this vulnerability.