CVE-2026-55056 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 • 07/15/2026
A heap-based buffer overflow vulnerability exists within Microsoft Office applications that enables unauthorized attackers to execute arbitrary code on a target system with local privileges. This critical flaw originates from improper input validation and memory management practices within the office suite's processing routines for various document formats. The vulnerability specifically manifests when the application attempts to write data beyond the allocated heap memory boundaries while handling maliciously crafted office documents or files. Attackers can exploit this weakness by preparing specially constructed documents that trigger the buffer overflow during normal document parsing operations, allowing them to overwrite adjacent memory locations and potentially redirect execution flow to malicious code.
The technical implementation of this vulnerability aligns with common software security weaknesses categorized under CWE-122, which addresses heap-based buffer overflows in programming environments. This type of vulnerability represents a significant concern within the attack surface of enterprise systems since Microsoft Office remains one of the most widely deployed software applications globally. The exploitation typically requires social engineering tactics to deliver malicious documents to unsuspecting users who open them with vulnerable office applications. Once executed, the attacker gains local code execution privileges on the target system, potentially escalating to higher privilege levels depending on the user context and system configuration.
The operational impact of this vulnerability extends beyond simple local code execution, as it provides attackers with a persistent foothold for further exploitation within corporate networks. The attack vector commonly involves phishing campaigns where users receive emails containing malicious attachments such as word documents, excel spreadsheets, or powerpoint presentations that contain embedded malicious code. This vulnerability directly maps to several techniques described in the MITRE ATT&CK framework under initial access and execution phases, particularly leveraging spearphishing attachments and legitimate user applications for code execution. Organizations may experience significant operational disruption when this vulnerability is exploited, as attackers can establish backdoors, exfiltrate sensitive data, or deploy additional malware payloads through the compromised office applications.
Effective mitigation strategies require a multi-layered approach combining software updates, administrative controls, and user awareness training. Microsoft has released security patches addressing this vulnerability through regular security updates, making it essential for organizations to maintain up-to-date systems with the latest cumulative security fixes. Additional protective measures include implementing application whitelisting policies that restrict execution of untrusted office documents, configuring email filtering systems to detect potentially malicious attachments, and enabling macro security settings within office applications. Network segmentation and monitoring solutions should be deployed to detect anomalous behavior patterns that may indicate exploitation attempts. Regular vulnerability assessments and penetration testing help identify systems that remain vulnerable due to delayed patching or misconfigurations. Organizations should also consider implementing endpoint detection and response solutions that can identify suspicious memory access patterns indicative of buffer overflow exploitation attempts.