CVE-2026-64919 in 365 Apps for Enterprise
Summary
by MITRE • 08/11/2026
Stack-based buffer overflow in Microsoft Office Access allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 08/11/2026
A stack-based buffer overflow vulnerability exists in Microsoft Office Access that enables unauthorized attackers to execute arbitrary code locally on affected systems. This critical security flaw resides within the application's handling of malformed input data during database operations, specifically when processing certain file formats or user-supplied information. The vulnerability stems from insufficient bounds checking mechanisms in the memory allocation processes, allowing attackers to overwrite adjacent stack memory locations with malicious payload data. When a user opens a specially crafted malicious file or interacts with vulnerable database components, the application fails to validate input size limits, leading to stack corruption that can be exploited to redirect program execution flow.
The technical implementation of this vulnerability follows established patterns for stack-based buffer overflows as classified under CWE-121, where insufficient bounds checking allows attackers to write beyond allocated memory boundaries. The flaw typically manifests when Office Access processes database records, query results, or imported data structures that exceed predetermined buffer limits. Attackers can leverage this weakness through various attack vectors including email attachments, malicious documents, or compromised network shares. The exploitation process often involves crafting specific input sequences that cause the stack pointer to be overwritten with controlled values, enabling code execution at privilege levels corresponding to the running Office Access process.
The operational impact of this vulnerability extends beyond simple local privilege escalation scenarios, as it provides attackers with persistent access to target systems and potential lateral movement capabilities within network environments. Successful exploitation can result in complete system compromise, data exfiltration, or deployment of additional malware payloads. The vulnerability affects Microsoft Office Access versions prior to specific security updates, making organizations running outdated software particularly susceptible. Network-based attacks become more feasible when attackers can deliver malicious content through web applications or file sharing services that users may inadvertently open. Organizations with default Office installations or those using legacy database configurations face heightened risk due to the widespread availability of attack tools targeting these specific memory corruption vulnerabilities.
Mitigation strategies should prioritize immediate deployment of Microsoft security patches addressing this vulnerability, alongside comprehensive network monitoring for suspicious file access patterns and user behavior anomalies. System administrators should implement application whitelisting policies to restrict execution of unauthorized Office Access components and establish regular vulnerability assessment procedures to identify unpatched systems. Network segmentation and privilege separation measures can limit potential damage from successful exploitation attempts. Additionally, user education programs should emphasize safe document handling practices and encourage reporting of suspicious file attachments or database interactions. Security teams must monitor exploit indicators such as anomalous memory access patterns, unexpected process creation, or unusual network connections that may indicate attempted exploitation of this stack-based buffer overflow vulnerability. The implementation of exploit prevention technologies including DEP, ASLR, and code signing enforcement can provide additional defense layers against successful exploitation attempts.