TeamViewer Vulnerability Allows Malicious Hosts to Execute Code on Technician Systems

High-Severity Flaw Identified

Cybersecurity firm Remedio has disclosed a high-severity vulnerability in TeamViewer, tracked as CVE-2026-111585 with a CVSS score of 8.8. This flaw is an integer overflow within the remote-control screen processing component of TeamViewer clients across multiple operating systems, including Windows, macOS, Linux, and Android.

Exploitation Mechanism

The vulnerability can be exploited if a user establishes a remote-control session to an attacker-controlled or compromised host. The issue stems from how the host's screen dimensions are transmitted and used by the viewer. A malicious host can announce screen dimensions that cause an integer overflow when the viewer allocates an in-memory pixel buffer for decompressing screen updates. This can lead to out-of-bounds writes.

While hardware video decoders are typically used, a malicious host can force the viewer to use the vulnerable software decoding path by refusing to negotiate video codecs. This allows the attacker to control both the declared surface size and the screen updates that trigger the buffer overflow.

Impact of Exploitation

Successful exploitation of CVE-2026-111585 can result in a denial-of-service condition, causing the viewer's TeamViewer application to crash repeatedly. More critically, Remedio demonstrated that the flaw can be used to achieve arbitrary code execution on the viewer's system. By corrupting a live object and overwriting a pointer, attackers can redirect calls to execute their own code, bypassing existing protections.

Prerequisites for Attack

The vulnerability can be triggered from within an ordinary, established TeamViewer session using only messages supported by the protocol. An accepted session to a malicious or compromised host is the primary requirement for an attacker to exploit this flaw.