CVE-2026-55124 in Office
Summary
by MITRE • 07/14/2026
Improper validation of specified type of input in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 07/15/2026
This vulnerability represents a critical security flaw in Microsoft Office Word that stems from inadequate input validation mechanisms within the application's processing pipeline. The issue manifests when the software fails to properly validate the data types and formats of user-supplied inputs, creating potential attack vectors for malicious actors seeking to exploit the system locally. Such improper validation typically occurs during document parsing operations where Word processes various file formats including .doc, .docx, and other Microsoft Office document types that may contain embedded objects or references.
The technical implementation flaw allows attackers to craft specially formatted documents or input data that bypasses normal security checks, enabling unauthorized information disclosure within the local system environment. This type of vulnerability commonly falls under the CWE-20 category known as "Improper Input Validation" which represents one of the most prevalent classes of software vulnerabilities in enterprise applications. The weakness creates opportunities for attackers to manipulate the application's behavior through carefully crafted inputs that exploit parsing inconsistencies or missing validation routines.
From an operational perspective, this vulnerability poses significant risks to organizations as it enables local information disclosure attacks without requiring elevated privileges or complex exploitation techniques. Attackers can leverage this flaw to access sensitive data stored locally on victim systems, potentially including documents, configuration files, or other system resources that should remain protected. The attack surface extends beyond simple document viewing to encompass any functionality that processes external input within the Word application context, making it particularly dangerous in enterprise environments where users frequently open documents from untrusted sources.
The mitigation strategies for this vulnerability should include immediate deployment of Microsoft security patches and updates as released through regular Windows Update cycles. Organizations must implement comprehensive input sanitization procedures that validate all document elements before processing, including implementing strict type checking and format validation routines. Additionally, administrators should consider deploying application whitelisting solutions to restrict execution of untrusted Office documents and establish robust monitoring protocols to detect anomalous behavior patterns associated with exploitation attempts. This vulnerability aligns with several ATT&CK tactics including T1059 for command and scripting interpreter and T1074 for data staging, emphasizing the need for layered defense mechanisms that address both endpoint protection and network-based monitoring approaches to prevent successful exploitation attempts.