CVE-2026-69442 in Office
Summary
by MITRE • 09/09/2026
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office suite, specifically manifesting as a heap-based buffer overflow condition that can be exploited remotely via network vectors. This type of defect arises when software operations write data beyond the allocated boundaries of a memory block on the heap, overwriting adjacent memory structures and potentially allowing an attacker to manipulate program execution flow. In the context of Microsoft Office applications, such vulnerabilities are frequently triggered by processing specially crafted documents or files that contain malformed content designed to exploit parsing logic errors within the application's rendering engine or data handling components. The severity is amplified by the fact that exploitation can occur over a network, meaning an attacker does not need physical access or local user interaction beyond convincing a victim to open a malicious file sent through email or hosted on a web server.
From a technical perspective, heap-based buffer overflows are particularly dangerous because they allow for arbitrary code execution with the privileges of the affected application process. When the overflow occurs, it may corrupt internal data structures such as function pointers or exception handlers located in adjacent memory regions. If an attacker can control these overwritten values, they can redirect program execution to shellcode injected into the heap space. This capability enables full system compromise, including installation of malware, exfiltration of sensitive data, and establishment of persistent backdoors. The remote nature of this attack vector significantly increases its risk profile compared to local-only exploits, as it facilitates widespread automated attacks against organizations that rely heavily on Microsoft Office for daily operations.
The operational impact of such a vulnerability is severe, potentially leading to complete loss of confidentiality, integrity, and availability within affected systems. An attacker leveraging this flaw could gain administrative control over compromised machines, facilitating lateral movement across the network or targeting high-value assets stored locally. Furthermore, because Microsoft Office applications are ubiquitous in enterprise environments, successful exploitation can lead to large-scale breaches affecting numerous endpoints simultaneously if patching is delayed. The ability to execute code remotely also means that social engineering tactics such as phishing campaigns become highly effective delivery mechanisms for this exploit, requiring robust user awareness training alongside technical controls.
Mitigation strategies must focus on both immediate remediation and long-term defense-in-depth measures. The primary action is the prompt application of security updates provided by Microsoft to patch the underlying code defect causing the buffer overflow. Organizations should ensure that automatic update services are enabled for all endpoints running affected versions of Office. Additionally, implementing Application Control policies such as Windows Defender Application Control or AppLocker can restrict execution of untrusted scripts and binaries, thereby limiting the impact even if an exploit succeeds. Network segmentation and strict email filtering solutions that inspect attachments for malicious content before delivery to end-users also serve as critical layers of defense. Regular vulnerability assessments and penetration testing should be conducted to identify similar weaknesses in custom macros or add-ins integrated with Office applications.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-120, which defines buffer copy without checking size limits, specifically the heap variant known as CWE-122: Heap-based Buffer Overflow. In terms of adversary tactics and techniques, this exploit maps to MITRE ATT&CK technique T1195.002, Supply Chain Compromise: Compromise Software Supply Chain, if delivered via compromised documents from trusted sources, or more commonly T1189 Drive-by Client Execution for web-hosted payloads and T1204 User Execution for phishing-based delivery methods. Understanding these mappings helps security teams prioritize detection rules in endpoint detection and response (EDR) solutions to monitor for suspicious process creation patterns indicative of heap exploitation attempts.