CVE-2026-70319 in Office
Summary
by MITRE • 08/12/2026
Improper input validation in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
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Analysis
by VulDB Data Team • 08/12/2026
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 Word fails to properly validate user-supplied data during document parsing operations, creating opportunities for malicious actors to exploit the software's handling of malformed or unexpected input. Such weaknesses typically arise from insufficient sanitization of document elements including embedded objects, macros, or structured markup that could contain crafted payloads designed to trigger unintended behavior. The vulnerability falls under the broader category of input validation failures that are systematically catalogued in the Common Weakness Enumeration database as CWE-20, which specifically addresses "Improper Input Validation" and encompasses numerous subtypes including weak input filters, insufficient sanitization, and inadequate boundary checks.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more severe attack vectors depending on the execution environment. When an attacker successfully exploits this flaw, they can manipulate Word's internal processing mechanisms to extract sensitive data from the local system or gain insights into system configuration that would normally remain protected. This type of local information disclosure can serve as a foothold for further exploitation, allowing adversaries to map system resources, identify installed software versions, or discover potentially vulnerable components within the attack surface. The vulnerability is particularly concerning in enterprise environments where Word documents are frequently exchanged and processed, as it could enable attackers to harvest sensitive corporate data or establish persistence mechanisms through carefully crafted malicious documents.
From a threat modeling perspective, this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, specifically under the reconnaissance phase where adversaries gather information about target systems before launching more sophisticated attacks. The ability to perform local information disclosure creates opportunities for attackers to conduct passive reconnaissance while processing documents, potentially identifying system configurations, user permissions, or installed security tools that could inform subsequent attack phases. Security professionals should recognize this as an indicator of broader application security weaknesses that may exist in similar input handling mechanisms throughout Microsoft Office applications, particularly those that process untrusted content such as email attachments, shared documents, or collaborative editing environments.
Mitigation strategies for this vulnerability should encompass both immediate defensive measures and longer-term architectural improvements to prevent similar issues from occurring in future software releases. Organizations should implement strict document validation policies that include automated scanning of incoming Word documents for suspicious elements, enforcement of secure configuration settings within Office applications, and regular security updates from Microsoft that address known vulnerabilities. Additionally, security teams should consider deploying network-level controls such as email filtering systems that can identify and quarantine potentially malicious documents before they reach end-user workstations. The implementation of principle of least privilege access controls and enhanced monitoring of document processing activities can further reduce the potential impact of successful exploitation attempts. Regular vulnerability assessments and penetration testing focused on document processing components should be conducted to identify additional weaknesses in input validation mechanisms that could provide similar attack vectors for adversaries seeking to compromise Microsoft Office environments.