CVE-2026-55017 in Office
Summary
by MITRE • 07/14/2026
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/14/2026
A heap-based buffer overflow vulnerability in Microsoft Office presents a critical security risk that enables arbitrary code execution by unauthorized attackers within local environments. This flaw resides in the memory management handling of Office applications when processing specially crafted malicious files or content. The vulnerability stems from insufficient bounds checking during heap allocation operations, allowing attackers to overwrite adjacent memory locations with malicious payload data. When Office processes malformed input through its document parsing engines, the application fails to validate buffer boundaries properly, creating opportunities for attackers to manipulate heap memory structures and redirect execution flow.
The technical implementation of this vulnerability typically involves crafting malicious Office documents that trigger specific parsing paths within the application's memory management subsystem. Attackers exploit this by placing data beyond allocated buffer limits, potentially overwriting function pointers, return addresses, or other critical control data structures in the heap memory space. This type of vulnerability falls under CWE-121 Heap-based Buffer Overflow classification, which specifically addresses buffer overflows occurring in heap memory regions where dynamic allocation occurs. The exploitation mechanism often leverages the predictable nature of heap layouts and memory allocation patterns to achieve reliable code execution.
The operational impact of this vulnerability extends beyond simple privilege escalation scenarios as it provides attackers with persistent local execution capabilities within Office environments. Once successfully exploited, attackers can execute malicious code with the privileges of the targeted Office application user, potentially leading to complete system compromise if users have administrative rights. The attack surface includes various Microsoft Office formats such as word processing documents, spreadsheets, presentations, and other file types that utilize the vulnerable parsing libraries. This vulnerability aligns with ATT&CK technique T1059.005 Command and Scripting Interpreter for Office Applications, where adversaries leverage legitimate office applications to execute malicious code.
Mitigation strategies should focus on immediate patch management through Microsoft security updates that address the specific heap overflow conditions in Office components. Organizations must implement comprehensive application whitelisting policies to restrict execution of untrusted Office documents and utilize sandboxing mechanisms for document processing. Network segmentation and user privilege reduction practices can limit the potential damage from successful exploitation attempts. Security monitoring should include detection of anomalous memory allocation patterns and suspicious heap operations within Office processes, leveraging endpoint detection and response solutions that can identify early indicators of buffer overflow exploitation attempts. Regular security assessments and vulnerability scanning of Office installations help identify systems running outdated versions that may be susceptible to this class of heap-based buffer overflow attacks.