CVE-2026-78510 in Office
Summary
by MITRE • 09/09/2026
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 • 09/09/2026
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 more data to a dynamically allocated block of memory on the heap than it was intended to hold. In the context of Microsoft Office Word, this typically arises during the processing of complex document structures or specific file formats that involve intricate parsing logic. When an attacker crafts a maliciously formatted document containing oversized fields or malformed objects, they can overwrite adjacent memory locations on the heap. This overwriting capability allows for arbitrary code execution because the attacker can manipulate function pointers or exception handlers stored in nearby memory regions to redirect program flow toward shellcode injected into the buffer itself.
From a technical perspective, this vulnerability aligns with Common Weakness Enumeration identifier CWE-120, which classifies buffer copies without checking size limits as a fundamental programming error leading to memory corruption. The exploitation of such flaws often leverages techniques categorized under MITRE ATT&CK framework tactics related to initial access and execution. Specifically, attackers may utilize document-based phishing campaigns where the malicious file is delivered via email or network shares. Once opened by an unsuspecting user within Word, the exploit triggers automatically without requiring additional interaction in many cases, facilitating remote code execution with the privileges of the current user account. This capability makes it a potent vector for deploying malware, establishing persistence, and moving laterally across enterprise networks if left unpatched.
The operational impact of this vulnerability is severe due to its potential for widespread compromise within organizations relying on Microsoft Office products for daily operations. Successful exploitation grants an unauthorized attacker full control over the affected system, enabling them to install programs, view, change, or delete data, and create new accounts with full user rights. In a networked environment, this can lead to significant data breaches, intellectual property theft, and disruption of business continuity. Furthermore, because Microsoft Office is ubiquitous across corporate infrastructures, the attack surface is extensive, making it a high-value target for cybercriminal groups seeking scalable entry points into secure networks.
Mitigation strategies must prioritize immediate patching through official security updates provided by Microsoft to address the underlying memory management flaws in Word's parsing engines. Organizations should enforce strict email filtering policies that inspect attachments for known malicious patterns and restrict macro execution unless explicitly required and vetted. User awareness training is also critical, as social engineering often accompanies such exploits; employees must be educated to recognize suspicious documents even from trusted sources if they exhibit anomalous behavior or originate from unexpected contexts. Additionally, implementing application whitelisting and leveraging advanced endpoint protection solutions can help detect and block the execution of unauthorized code resulting from this vulnerability before it causes significant damage.