CVE-2026-83764 in Windows
Summary
by MITRE • 10/14/2026
Incorrect authorization in Windows Clipboard User Service allows an authorized attacker to disclose information locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified within the Windows Clipboard User Service represents a critical flaw in access control mechanisms, specifically categorized under CWE-269: Improper Control of Interaction with Untrusted Input or CWE-732: Incorrect Permission Assignment for Critical Resource. This service is responsible for managing clipboard operations across user sessions and applications on Microsoft Windows operating systems. The core technical issue stems from an insufficient verification process during authorization checks, which allows a locally authenticated attacker to bypass intended security restrictions. By exploiting this misconfiguration, the attacker can interact with sensitive data stored in or processed by the clipboard without possessing the necessary privileges for such actions. This failure indicates that the service does not adequately validate whether the requesting entity has legitimate authority to access specific clipboard contents or metadata, leading to a breakdown in the principle of least privilege.
From an operational perspective, this vulnerability enables local information disclosure attacks where sensitive data can be exfiltrated by malicious software running under the context of a lower-privileged user account. Attackers who have already gained foothold on the system through phishing, drive-by downloads, or other initial access vectors can leverage this flaw to harvest passwords, authentication tokens, personally identifiable information, or proprietary code snippets that users may have copied into their clipboard. The impact is particularly severe in environments where sensitive data is frequently handled via copy-paste operations, such as financial institutions, healthcare facilities, and corporate offices dealing with confidential documents. Since the attack requires local execution, it aligns with MITRE ATT&CK technique T1059: Command and Scripting Interpreter or more specifically T1005: Data from Local System, facilitating post-exploitation data staging before potential exfiltration to external command-and-control servers.
The exploitation of this vulnerability does not typically require elevation of privilege beyond the current user context but relies on social engineering or prior compromise to place malicious code in a position where it can invoke clipboard APIs improperly. Once triggered, the attacker gains read access to clipboard data that should be restricted to authorized applications and users only. This compromises confidentiality integrity for any sensitive information temporarily held in memory by the clipboard service. Mitigation strategies primarily involve applying vendor-provided security patches that correct the authorization logic within the Windows Clipboard User Service components. Administrators must ensure timely deployment of these updates across all endpoints to close this gap in access control. Additionally, implementing application whitelisting and monitoring for unusual clipboard API calls can provide detection capabilities against exploitation attempts. Users should also be educated on best practices regarding sensitive data handling, such as avoiding copying passwords directly into the clipboard when possible, thereby reducing the attack surface even if technical controls are not immediately updated.