Attack Chain

1. Attacker gains initial JavaScript execution within Electerm’s renderer process, possibly via a malicious plugin or XSS.
2. The attacker crafts a malicious widget identifier containing path traversal sequences (e.g., ../).
3. The malicious widget identifier is passed to the runWidget function via an asynchronous IPC handler.
4. The runWidget function concatenates the unsanitized widget identifier into a file path: widget-${widgetId}.js.
5. The resulting file path includes the path traversal sequences, allowing access to arbitrary files.
6. The require() function attempts to load and execute the JavaScript file at the attacker-controlled path.
7. If the path traversal is successful, an arbitrary JavaScript file is executed with Electerm process privileges.
8. The attacker achieves arbitrary code execution, leading to complete system compromise.

Impact

Successful exploitation of this vulnerability grants an attacker local code execution with the privileges of the Electerm process. This enables them to perform actions such as installing malware, stealing sensitive data, or compromising the entire system. The vulnerability affects Electerm users on Windows 10 and Linux systems who are running versions prior to 3.7.16. A successful attack could lead to complete system compromise.

Recommendation

• Upgrade Electerm to version 3.7.16 or later to patch CVE-2026-43940.
• Deploy the Sigma rule Detect Suspicious Electerm Widget Loading to your SIEM and tune for your environment to detect path traversal attempts.
• Enable process creation logging on Windows and Linux systems to enhance visibility and enable the Detect Suspicious Electerm Widget Loading rule.