CVE-2026-69360 in Office
Summary
by MITRE • 09/08/2026
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 09/08/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office Word 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 Word, this defect is typically triggered by processing specially crafted documents or files that exploit parsing logic errors within the application's rendering engine or document structure handlers. The attacker constructs input data designed to exceed the expected size limits defined for specific internal buffers, thereby overwriting adjacent memory locations with malicious payload code. This overwrite operation disrupts the normal flow of execution and allows an unauthorized remote actor to gain control over the affected system by executing arbitrary commands within the security context of the current user.
From a technical perspective, heap-based buffer overflows are particularly dangerous because they can be triggered remotely without requiring physical access or local authentication if the vulnerability is exploitable through network-delivered content such as email attachments or web-hosted documents accessed via browser integration. The operational impact is severe, potentially leading to complete system compromise. An attacker who successfully exploits this flaw could install programs, view, change, or delete data, or create new accounts with full user rights. This effectively neutralizes the security posture of the affected machine, allowing for persistent access and lateral movement within a network environment if the compromised host is part of an enterprise infrastructure. The ability to execute code over the network significantly lowers the barrier to entry for attackers compared to local-only exploits, making this vulnerability highly attractive in automated scanning campaigns or targeted phishing attacks aimed at corporate environments relying heavily on Microsoft Office products.
This vulnerability aligns with Common Weakness Enumeration (CWE) identifier CWE-120, which classifies buffer copy without checking size limits, and more specifically points toward heap corruption mechanisms often associated with improper validation of input data lengths before memory allocation or copying operations. In terms of the MITRE ATT&CK framework, this exploit scenario maps to techniques involving remote code execution through document parsing vulnerabilities, such as T1203 Exploitation for Client Execution where attackers leverage trusted applications like Office Word to run malicious payloads on target systems. The attack vector is classified as Network (Attack Vector: NETWORK), indicating that the vulnerability can be exploited from a remote location over a network without requiring user interaction beyond opening or viewing the malicious file, although some variants may require social engineering tactics to persuade users into enabling macros or trusting content sources depending on specific configuration settings and version specifics.
Mitigation strategies must focus on both immediate remediation and long-term defensive posture improvements. The primary corrective action is to apply the latest security updates provided by Microsoft for all affected versions of Office Word, as these patches typically include bounds checking fixes and improved input validation logic within the vulnerable components. Organizations should enforce strict patch management policies to ensure timely deployment of critical security releases across all endpoints. Additionally, implementing application control solutions such as Windows Defender Application Control or AppLocker can restrict the execution of untrusted scripts and binaries even if an exploit succeeds in placing malicious code on disk. Network segmentation and firewall rules that limit inbound traffic from untrusted sources reduce the attack surface for remote exploitation attempts. Furthermore, user awareness training regarding phishing tactics is essential to prevent social engineering efforts that might trick users into opening malicious documents despite technical controls being partially effective against automated exploits.