CVE-2026-92371 in Full Client
Summary
by MITRE • 09/29/2026
TeamViewer Full Client and Host for Linux prior version 15.82 contains an improper path validation vulnerability in the Cloud Session Recording (CSR) functionality. By exploiting a race condition during path validation and subsequent file access, a local authenticated attacker may cause privileged file operations in unintended locations on the affected system.
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Analysis
by VulDB Data Team • 09/29/2026
The vulnerability identified in TeamViewer Full Client and Host for Linux prior to version 15.82 represents a critical security flaw within the Cloud Session Recording functionality, specifically categorized under improper path validation mechanisms. This issue stems from a race condition that occurs during the process of validating file paths before subsequent access operations are executed. In secure software design, it is imperative that applications strictly validate and canonicalize all user-supplied or dynamically generated file paths to ensure they reside within an expected directory structure. However, in this specific implementation, the validation step and the actual file system operation are not performed atomically. This temporal gap allows a local authenticated attacker to manipulate the state of the target path between the moment it is checked for validity and the moment it is accessed or written to by the application process running with elevated privileges.
From a technical perspective, this flaw aligns closely with Common Weakness Enumeration (CWE) categories such as CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') and CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'). The core issue lies in the lack of atomicity in the file handling logic. When an application checks if a path is safe, it typically verifies that the path does not contain directory traversal sequences like ".." or points outside a designated sandboxed area. If another process modifies the symbolic link or directory structure at that specific location between the check and the write operation, the application may inadvertently operate on a file located in an arbitrary system directory rather than the intended recording storage location. This behavior effectively bypasses the security controls designed to restrict file operations to safe zones.
The operational impact of this vulnerability is significant due to the privilege level at which TeamViewer typically operates. As remote desktop and support software, TeamViewer often requires administrative or root-level permissions on Linux systems to capture screen data, manage input devices, and maintain persistent connections. By exploiting this race condition, a local authenticated attacker can trick the privileged process into writing files to arbitrary locations within the file system. This capability enables several malicious outcomes, including overwriting critical configuration files, injecting malicious scripts into startup directories for persistence, or corrupting essential system binaries. Such actions can lead to full system compromise, allowing the attacker to escalate privileges further, install backdoors, or disrupt service availability by damaging core operating system components.
This vulnerability also maps directly to tactics within the MITRE ATT&CK framework, particularly those related to Privilege Escalation and Persistence. The ability to write files in unintended locations facilitates techniques such as T1059: Command and Scripting Interpreter if malicious scripts are placed in executable paths, or T1546: Event Triggered Execution if specific system events trigger the execution of these injected files. Furthermore, the exploitation method falls under T1203: Exploitation for Client Execution if the attacker leverages this flaw to deploy additional payloads that execute with higher privileges than the initial foothold provided by local authentication.
Mitigation strategies must prioritize immediate software updates and robust defensive configurations until patches are applied. The primary remediation is to upgrade TeamViewer Full Client and Host on Linux systems to version 15.82 or later, where this race condition has been addressed through improved synchronization mechanisms and stricter path validation logic that ensures atomicity between checks and operations. In environments where immediate patching is not feasible, administrators should enforce strict least-privilege principles by running TeamViewer processes under restricted user accounts with minimal file system permissions wherever possible. Additionally, implementing mandatory access control systems such as SELinux or AppArmor can provide a critical layer of defense by restricting the specific paths and operations that the TeamViewer process is allowed to perform, thereby neutralizing the impact even if an attacker successfully exploits the race condition. Regular auditing of file integrity in directories associated with remote support tools can also aid in early detection of such exploitation attempts.