CVE-2026-97740 in 365 Apps for Enterprise
Summary
by MITRE • 10/15/2026
Exposure of sensitive system information to an unauthorized control sphere in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability described involves the improper exposure of sensitive system information within Microsoft Office Excel, specifically allowing an unauthorized actor to retrieve this data through network-based interactions. This flaw represents a classic case of Information Disclosure, where internal application states or configuration details that are intended for local use only become accessible via remote protocols. In many instances involving Excel and similar productivity suites, such exposure often stems from how the application handles requests over HTTP or other network interfaces when processing documents, macros, or embedded objects. The underlying technical flaw typically lies in insufficient validation of input sources or improper handling of error responses that inadvertently leak stack traces, file paths, server versions, or internal configuration parameters to the client side. This behavior violates fundamental security principles regarding the separation of privileged and unprivileged contexts, allowing an attacker who can trigger specific actions within Excel over a network to gather intelligence about the target environment without needing direct authentication or elevated privileges on the host system.
From a technical perspective, this vulnerability aligns with Common Weakness Enumeration (CWE) categories such as CWE-209: Generation of Error Message Containing Sensitive Information and CWE-200: Exposure of Sensitive Information to an Unauthorized Actor. The operational impact is primarily reconnaissance-oriented but serves as a critical precursor for more severe attacks. By obtaining detailed system information, an attacker can identify the specific version of Excel installed, detect underlying operating system characteristics, or uncover network topology details embedded in document metadata or server responses. This intelligence gathering reduces the effort required to craft targeted exploits against known vulnerabilities associated with those specific software versions and configurations. Furthermore, if the exposed information includes session tokens, internal IP addresses, or database connection strings inadvertently cached by the application during normal operation, the risk escalates from mere disclosure to potential unauthorized access or lateral movement within a corporate network.
The attack vector for this vulnerability is typically remote, requiring an attacker to interact with Excel through web-based interfaces such as Office Online, SharePoint integration points, or any service that processes Excel files over HTTP/HTTPS. This makes it particularly dangerous in enterprise environments where documents are frequently shared and processed via cloud services or internal portals. An adversary could construct a malicious document or manipulate network requests to trigger the information leakage mechanism during normal file opening or editing operations. Because this occurs over a standard web protocol, firewalls may not block the traffic as they would with more aggressive exploit attempts, allowing the attacker to remain undetected while collecting valuable system intelligence. The persistence of this issue highlights gaps in how modern office applications sanitize output and manage state when interacting with external network resources.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Organizations should immediately apply all available security updates from Microsoft, as these patches typically include fixes for input validation logic and stricter sanitization of error messages returned to clients. It is also critical to configure Excel settings to disable unnecessary features such as ActiveX controls or macro execution unless strictly required by business operations, thereby reducing the attack surface. Network-level defenses should be implemented to monitor for unusual patterns in HTTP traffic that might indicate automated reconnaissance attempts against Office services. Additionally, adopting a principle of least privilege ensures that even if information is disclosed, it does not reveal credentials or keys necessary for deeper compromise. Regular security audits and penetration testing focused on web application interactions with office suites can help identify similar misconfigurations before they are exploited by malicious actors aiming to map out network infrastructure.