TeamViewer fixes flaw that could let remote hosts attack viewers

TeamViewer has fixed a critical flaw that allows a remote host in a session to attack the viewer after the user initiates a remote-control connection. In Remedio researcher Omri Dar’s technical account, the attacker is the host and the victim is the viewer, with the host able to cause the viewer’s TeamViewer to crash and, on some platforms, to run code on the viewer’s machine.

The issue relies on the viewer allocating memory based on the host’s reported screen size; when that calculation overflows, subsequent screen data can be written past allocated bounds. The demonstration of potential code execution was shown on Windows, but TeamViewer has not confirmed a network-only exploit and notes that the Windows proof-of-concept was not demonstrated over the network in the public write‑up. The flaw is tracked as CVE-2026-111585 and carries a CVSS score of 8.8, in the high range.

TeamViewer states that the vulnerability affects all versions prior to 15.83 across the Full Client, Portable edition and Android Remote Control app on Windows, Linux, and macOS, while the Host appears not to be affected in the bulletin; however, the 15.83 update also resolves two other high‑severity flaws in that same bulletin that do affect the Host, so users running the Host should update as well.

The vulnerability was disclosed publicly on 29 October by Dar, with TeamViewer issuing the fixed build in version 15.83. There is no indication of observed exploitation in the wild, and the vulnerability is not listed in CISA’s Known Exploited Vulnerabilities catalog as of 29 October. The publication notes that updating to 15.83 or later is the recommended remediation, and that Remedio reported no attacks and did not release exploit code.