CVE-2025-64990 Overview
CVE-2025-64990 is a command injection vulnerability in TeamViewer Digital Employee Experience (DEX), formerly known as 1E DEX. The flaw exists in the 1E-Explorer-TachyonCore-LogoffUser instruction in versions prior to V21.1. Improper input validation allows authenticated attackers with Actioner privileges to inject arbitrary commands. Successful exploitation enables remote execution of elevated commands on devices connected to the platform. TeamViewer published security bulletin TV-2025-1006 to address the issue.
Critical Impact
Authenticated Actioners can execute arbitrary elevated commands on any endpoint managed by TeamViewer DEX, providing a path to full device compromise across the managed fleet.
Affected Products
- TeamViewer Digital Employee Experience (formerly 1E DEX)
- 1E-Explorer-TachyonCore-LogoffUser instruction
- All versions prior to V21.1
Discovery Timeline
- 2025-12-11 - CVE-2025-64990 published to NVD
- 2026-01-14 - Last updated in NVD database
Technical Details for CVE-2025-64990
Vulnerability Analysis
The vulnerability is a command injection flaw [CWE-20] in the 1E-Explorer-TachyonCore-LogoffUser instruction shipped with TeamViewer DEX. The instruction accepts parameters that are passed to an underlying command execution context without sufficient validation or sanitization. An authenticated user holding the Actioner role can craft input that breaks out of the intended command structure and appends attacker-controlled commands. Because DEX instructions execute on agents deployed to managed endpoints with elevated privileges, the injected commands run with system-level rights on remote devices. The result is remote, elevated command execution scoped to any device the Actioner can target through the platform.
Root Cause
The root cause is improper input validation in the parameter handling of the LogoffUser instruction. User-supplied data is concatenated into a command string executed by the Tachyon agent rather than being treated as a structured argument. Without escaping or allow-listing, shell metacharacters and command separators reach the underlying interpreter.
Attack Vector
Exploitation requires network access to the DEX platform and an authenticated account with Actioner privileges. The attacker submits the 1E-Explorer-TachyonCore-LogoffUser instruction against one or more managed devices with a malicious payload embedded in the parameter that is supposed to identify the user session. The Tachyon agent on the targeted endpoint executes the injected commands with elevated privileges, giving the attacker arbitrary code execution on every device targeted by the instruction.
No public proof-of-concept exploit is available, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog. See the TeamViewer Security Bulletin TV-2025-1006 for vendor-supplied technical details.
Detection Methods for CVE-2025-64990
Indicators of Compromise
- Execution of 1E-Explorer-TachyonCore-LogoffUser instructions containing shell metacharacters such as ;, &, |, backticks, or $() in their parameters.
- Tachyon agent processes on managed endpoints spawning unexpected child processes such as cmd.exe, powershell.exe, or /bin/sh outside of normal logoff workflows.
- Audit log entries showing Actioner-privileged accounts issuing LogoffUser instructions at unusual volumes or against atypical device groups.
Detection Strategies
- Inspect DEX platform audit logs for LogoffUser instruction submissions and flag parameter values that do not match expected username formats.
- Correlate endpoint process telemetry with DEX instruction execution windows to identify Tachyon agent child processes that are not standard logoff binaries.
- Hunt for elevated command execution on endpoints originating from the Tachyon agent process tree shortly after instruction dispatch.
Monitoring Recommendations
- Forward DEX platform audit logs and Tachyon agent logs to a centralized SIEM for continuous review of Actioner activity.
- Alert on any new or modified custom instructions that wrap or invoke LogoffUser functionality.
- Track Actioner role assignments and changes, and review accounts that hold this privilege on a recurring basis.
How to Mitigate CVE-2025-64990
Immediate Actions Required
- Upgrade TeamViewer DEX to version V21.1 or later, which contains the fix from bulletin TV-2025-1006.
- Audit all accounts assigned the Actioner role and remove the privilege from users who do not require it.
- Review recent LogoffUser instruction executions for signs of abuse before applying the patch.
Patch Information
TeamViewer addressed the vulnerability in TeamViewer DEX V21.1. Administrators should plan an upgrade following vendor guidance in the TeamViewer Security Bulletin TV-2025-1006. The patch corrects input validation in the 1E-Explorer-TachyonCore-LogoffUser instruction so that parameters are no longer interpretable as shell commands.
Workarounds
- Restrict the Actioner role to a minimal set of trusted administrators until the upgrade is completed.
- Disable or restrict execution of the 1E-Explorer-TachyonCore-LogoffUser instruction at the platform level if business operations allow.
- Apply network segmentation and multi-factor authentication on DEX platform access to reduce the risk of credential-based abuse.
# Configuration example
# Verify installed TeamViewer DEX version and confirm it is V21.1 or later
# Then review Actioner role assignments in the DEX console:
# Settings > Permissions > Roles > Actioner
# Remove any accounts that do not require instruction execution rights.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
