CVE-2026-55029 in Office
Summary
by MITRE • 07/14/2026
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/14/2026
A heap-based buffer overflow vulnerability exists in Microsoft Office Excel that enables remote code execution when a maliciously crafted file is opened by an unsuspecting user. This critical security flaw resides in the application's handling of structured data within memory allocation processes, specifically affecting how Excel manages dynamic memory blocks during spreadsheet processing operations. The vulnerability stems from inadequate bounds checking mechanisms that fail to validate input data lengths before copying information into heap-allocated buffers. When a user opens a specially crafted excel file containing malicious data structures, the application attempts to write data beyond the allocated buffer boundaries, causing memory corruption that can be exploited by attackers to overwrite critical memory locations including return addresses and function pointers.
The technical exploitation of this vulnerability follows established patterns documented in the common weakness enumeration framework under cwe-121 heap-based buffer overflow. Attackers typically craft malicious excel files containing oversized data fields or malformed structured references that trigger the memory corruption when processed by Excel's parsing engine. The vulnerability operates at the application layer and requires user interaction to be exploited, making it a prime candidate for phishing attacks targeting corporate environments where excel usage is prevalent. This attack vector aligns with techniques described in the attack tree framework under initial access and execution categories, specifically leveraging social engineering to deliver malicious payloads through email attachments or file sharing platforms.
The operational impact of this vulnerability extends beyond simple code execution, potentially allowing attackers to establish persistent access within target environments. Successful exploitation can lead to complete system compromise, data exfiltration, and lateral movement throughout network infrastructures. Organizations relying heavily on excel for business operations face significant risk exposure, particularly in environments where users frequently open files from external sources or where privilege escalation opportunities exist. The vulnerability affects multiple versions of Microsoft Office and requires immediate attention due to its potential for widespread exploitation across enterprise networks.
Mitigation strategies should prioritize immediate deployment of microsoft security updates and patches addressing the identified heap overflow conditions. Organizations must implement strict email filtering policies and user education programs to reduce successful delivery of malicious excel files through social engineering attacks. Network segmentation and application whitelisting controls can limit the scope of potential exploitation by preventing unauthorized code execution attempts. Additional defensive measures include enabling exploit protection features within windows operating systems, configuring excel to disable automatic execution of macros, and implementing regular security assessments to identify potentially vulnerable installations. The vulnerability demonstrates the critical importance of maintaining current security patches and following principle of least privilege configurations in enterprise security architectures.