1. Summary
A vulnerability has been discovered and fixed in the TeamViewer Full and Host clients, which allows an authenticated user to bypass additional access controls prior to confirmation of the counterparty.
2. Vulnerability details
3. Affected software and versions
4. Solutions and mitigations
Update to the latest client version (15.74.5 or the latest version available).
Optional mitigation: If an immediate update of the client is not possible and the use of additional access controls is required, the access control setting “Control this computer – Allow after Confirmation” can be set as mitigation. This prevents exploitation. The access controls can be configured in the Client Settings – “Advanced Options > Advanced Settings for connections to this computer” or via Policies “Access Control (incoming connections)”.
5. Acknowledgments
We would like to thank V.Z. & M.M. for the discovery and responsible disclosure.