CVE-2026-105596 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 • 10/13/2026
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 more data to a dynamically allocated block of memory on the heap than it was intended to hold. In the context of Microsoft Office Access, this flaw is typically triggered by processing specially crafted files or input streams that contain malformed data structures exceeding expected bounds. The attacker leverages this discrepancy to overwrite adjacent memory locations, which can include function pointers, exception handlers, or other control flow mechanisms within the application's process space. Because heap overflows are often more complex and less predictable than stack-based ones, they require precise exploitation techniques to achieve reliable code execution without crashing the target system immediately.
The operational impact of this vulnerability is severe due to its potential for remote code execution via a network vector. An unauthorized attacker can exploit this flaw by tricking a user into opening a maliciously constructed Access database file or interacting with a compromised web service that serves such files through Microsoft Office Web Apps or similar integration points. Once the vulnerable component processes the crafted input, the overflow allows the injection and subsequent execution of arbitrary machine code within the security context of the current user. This grants the attacker full control over the affected system, enabling them to install malware, steal sensitive credentials, pivot to other network resources, or establish persistent backdoors. The ability to execute code remotely significantly lowers the barrier for entry compared to local-only exploits, making this a high-priority threat in enterprise environments where shared documents and automated data processing are common practices.
From an industry standards perspective, this vulnerability aligns with Common Weakness Enumeration identifier CWE-120, which classifies buffer copies without checking size limits as a fundamental memory safety error. Furthermore, the exploitation technique falls under MITRE ATT&CK framework tactics related to Initial Access and Execution, specifically leveraging user interaction or automated processing of untrusted data sources. The network-based nature of the attack also implicates CWE-94, which covers code injection vulnerabilities where attacker-controlled input is interpreted as executable code by a vulnerable component. Understanding these classifications helps in mapping the vulnerability to broader threat models and prioritizing remediation efforts based on established risk frameworks used by security operations centers globally.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. The primary defense is the timely application of vendor-provided security updates that address the specific memory handling routines responsible for the overflow. Organizations should prioritize deploying these patches to all endpoints running Microsoft Office Access, particularly those connected to untrusted networks or exposed to external users. Additionally, implementing strict file type validation and sandboxing mechanisms can limit the blast radius if an exploit is attempted. Security teams should also enforce least-privilege principles by restricting user permissions on shared drives where such files might reside, reducing the likelihood of accidental execution. Regular security awareness training for end-users regarding phishing attacks that deliver malicious Office documents remains a critical layer of defense against social engineering vectors that often precede technical exploitation of this flaw.