CVE-2026-42850: Kitty has a shell command injection

Synopsis

Shell command injection in the Kitty GPU-based terminal emulator (kovidgoyal/kitty) allows an attacker to inject arbitrary shell commands through an unescaped error response triggered by a crafted escape code. Exploitation requires the victim to connect to an attacker-controlled host using netcat or a similar tool, and the attacker must also be in a position to deliver the malicious escape code over that connection. Successful exploitation gives the attacker full command execution in the victim's active shell session. No fix version has been published yet; HarborGuard tracks the advisory and will surface a patched-image rebuild as soon as an upstream fix is available.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must be reachable over the network: the victim must initiate an outbound connection to an attacker-controlled host using netcat or a similar utility, exposing the terminal session to the malicious escape code.

• AuthenticationNot required

  No authentication is required on the attacker's side; the attacker does not need any account or credential on the victim's system to deliver the malicious payload.

• Victim interactionRequired

  The victim must actively connect to the attacker-controlled host using netcat or a similar tool, making this a social-engineering-dependent attack that requires deliberate victim participation.

• Attack complexityDetail

  Attack complexity is rated High, meaning specific preconditions must align: the victim must be running Kitty and must establish an outbound connection to the attacker at the right moment, introducing environmental dependencies beyond the attacker's direct control.

Blast Radius

• Reads files and data accessible to the victim's user account on the host, including environment variables, credentials, and SSH keys stored in the home directory.
• Executes arbitrary commands in the victim's active shell, allowing the attacker to install software, modify files, or pivot to other services the victim's account can reach.
• Achieves persistent access by writing authorized keys, cron jobs, or shell profile modifications under the victim's account.