CVE-2026-102849 in 365 Apps for Enterprise
Summary
by MITRE • 10/13/2026
Heap-based buffer overflow in Microsoft Office Access allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office Access application, specifically manifesting as a heap-based buffer overflow condition. This type of memory corruption error occurs when a program writes data beyond the allocated boundaries of a buffer located in the heap segment of computer memory. In the context of Microsoft Office Access, this defect is triggered by processing specially crafted files or inputs that exceed expected size limits or contain malformed structures. The attacker leverages this flaw to overwrite adjacent memory locations on the heap, which can lead to arbitrary code execution with the privileges of the currently logged-in user. Because the vulnerability allows for remote exploitation over a network, it represents a significant threat vector where an adversary does not need physical access to the target system or prior authentication credentials in many scenarios, particularly if the malicious content is delivered via email attachments or shared network resources that are automatically processed by the application.
From a technical perspective, heap-based buffer overflows differ from stack-based ones in their complexity and impact on memory management structures such as allocation metadata and linked lists within the heap manager. By carefully crafting the overflow payload, an attacker can manipulate these internal data structures to gain control over program execution flow. This often involves redirecting instruction pointers or function return addresses to shellcode injected into the buffer itself or elsewhere in memory. The ability to execute code remotely means that once exploited, the system may be fully compromised, allowing for further lateral movement within a network environment, installation of backdoors, exfiltration of sensitive data stored locally by Access databases, and potential pivoting to other systems connected to the same network infrastructure.
The operational impact of this vulnerability is severe due to its remote nature and high severity rating associated with code execution capabilities. Organizations relying on Microsoft Office Access for database management face significant risks including loss of data integrity, confidentiality breaches, and availability disruptions if attackers use the compromised system as a foothold for broader attacks. The ease of exploitation over a network lowers the barrier for entry, making it attractive to both automated worm-like malware and targeted threat actors seeking initial access points within corporate environments that still utilize legacy database technologies integrated with Microsoft Office suites.
Mitigation strategies must focus on immediate patching and defensive configuration changes. Administrators should apply all available security updates from Microsoft that address this specific heap overflow vulnerability in the affected versions of Office Access. In addition to patching, organizations should implement strict email filtering rules to block attachments containing potentially malicious database files or macros. User awareness training is also critical to prevent social engineering attacks where users might be tricked into opening untrusted .accdb or .mdb files. Furthermore, deploying application whitelisting solutions can restrict the execution of unauthorized binaries derived from exploit attempts, while network segmentation limits the ability of an attacker to move laterally after initial compromise. Regular vulnerability scanning and penetration testing should also be conducted to identify any instances where this flaw might still exist in unpatched systems within the enterprise environment.