CVE-2026-92370 in TeamViewer
Summary
by MITRE • 09/29/2026
An improper access control vulnerability in TeamViewer Full Client, Host, and related affected modules on Windows, Linux, and macOS allows an authenticated remote attacker to bypass user-configured permission settings during session establishment. By modifying access control parameters for restricted features, an attacker can perform actions that were explicitly denied by the victim's configuration. This may result in unauthorized actions and potentially lead to remote code execution on the target system.
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability described constitutes a critical failure in the implementation of access control mechanisms within TeamViewer Full Client, Host, and related modules across Windows, Linux, and macOS platforms. At its core, this flaw represents an improper privilege management issue where the application fails to enforce security policies consistently during the session establishment phase. Specifically, when a remote attacker establishes a connection with authenticated credentials, they are able to manipulate or bypass user-configured permission settings that were explicitly designed to restrict certain actions. This indicates that the software does not properly validate access rights against the configured policy before executing requested operations, allowing an adversary to override administrative restrictions through parameter modification during the handshake or session initialization process.
From a technical perspective, this vulnerability aligns with CWE-269, which classifies Improper Privilege Management as a category of weaknesses where software does not properly assign privileges to actors based on their roles and responsibilities. The specific mechanism involves modifying access control parameters for restricted features during the dynamic establishment of a remote session. By intercepting or altering these parameters before they are applied by the host system, an authenticated attacker can effectively elevate their permissions beyond what was granted in the initial configuration. This bypass is particularly dangerous because it occurs at a foundational level of the connection protocol, meaning that even if strict policies are defined in the user interface or administrative console, those safeguards are rendered ineffective during runtime execution due to this logic flaw.
The operational impact of this vulnerability is severe and multifaceted. While the immediate result is unauthorized access to restricted features such as file transfer, remote desktop control, or system configuration changes, the potential consequences extend far beyond simple policy violation. The ability to bypass these restrictions can lead directly to Remote Code Execution on the target system. If an attacker gains unrestricted access to sensitive modules or executes commands that were previously blocked by security policies, they may install malware, exfiltrate data, or use the compromised machine as a pivot point for further network intrusion. This transforms what might appear as a configuration bypass into a critical compromise of system integrity and confidentiality, potentially affecting entire organizational networks if TeamViewer is used extensively for remote support or administration.
In terms of industry frameworks, this vulnerability maps to MITRE ATT&CK technique T1078, Valid Accounts, specifically the aspect of using legitimate credentials to gain access while bypassing intended restrictions. It also relates to T1546, Event Triggered Execution, if the session establishment triggers specific scripts or processes that were meant to be restricted. The failure lies in the lack of robust server-side validation and state management during the authentication handshake, which is a common pattern in vulnerabilities where client-sent parameters are trusted without sufficient sanitization or policy enforcement checks on the host side.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Users should immediately apply any available patches released by TeamViewer that address this specific access control flaw. Until updates are applied, organizations should enforce strict network-level controls to limit who can initiate remote sessions using TeamViewer credentials. Implementing multi-factor authentication adds a layer of security but does not fully mitigate the risk if an attacker obtains valid credentials and exploits this logic flaw during session setup. Furthermore, administrators should review and minimize the permissions granted to standard user accounts within TeamViewer configurations, adhering to the principle of least privilege. Regular auditing of access logs can help detect anomalous behavior indicative of such bypass attempts, although detection may be challenging given that the actions appear as legitimate authenticated sessions until they result in unauthorized outcomes.