CVE-2026-43941 Overview
Electerm is an open-source terminal client supporting SSH, SFTP, Telnet, serial port, RDP, VNC, Spice, and FTP protocols. A vulnerability in versions 3.8.15 and prior allows arbitrary code execution through the terminal hyperlink handler. The application passes any URL clicked in the terminal directly to shell.openExternal without validating the protocol scheme. Attackers who control terminal output can craft malicious hyperlinks that execute arbitrary commands or access local files when clicked. Exploitation vectors include malicious SSH servers, compromised remote hosts, and plugins rendering terminal content. The vulnerability is tracked under CWE-88: Argument Injection.
Critical Impact
An attacker controlling terminal output can achieve arbitrary code execution on a victim's machine when the victim clicks a displayed hyperlink. No patches are publicly available at the time of publication.
Affected Products
- Electerm versions 3.8.15 and prior
- All platforms supported by Electerm (Windows, macOS, Linux)
- Electron-based deployments using the affected shell.openExternal handler
Discovery Timeline
- 2026-05-08 - CVE-2026-43941 published to NVD
- 2026-05-08 - Last updated in NVD database
Technical Details for CVE-2026-43941
Vulnerability Analysis
The vulnerability resides in Electerm's terminal hyperlink handler. When a user clicks a hyperlink rendered in the terminal, the application invokes Electron's shell.openExternal API with the raw URL string. The handler performs no validation of the URL scheme before passing it to the operating system.
Electron's shell.openExternal function delegates URL handling to the underlying operating system. Non-HTTP schemes such as file://, smb://, \\, and various OS-specific protocol handlers can trigger arbitrary application execution or grant access to local resources. Documentation for shell.openExternal explicitly warns that passing untrusted input enables remote code execution.
The attacker requires control over terminal output and user interaction in the form of a single click. The scope changes because code executes in the user's operating system context rather than the application sandbox. Confidentiality, integrity, and availability are all impacted.
Root Cause
The root cause is missing protocol validation in the hyperlink click handler. The application accepts arbitrary URL schemes without restricting them to a safe allowlist such as http: and https:. This violates Electron's security recommendations for handling user-clicked links from untrusted content sources.
Attack Vector
An attacker establishes control over content rendered in the Electerm terminal. Common scenarios include operating a malicious SSH server that emits ANSI escape sequences containing hyperlinks, compromising a legitimate remote host the victim connects to, or distributing a malicious Electerm plugin. The attacker crafts terminal output containing a hyperlink with a dangerous URL scheme. When the victim clicks the link, shell.openExternal invokes the corresponding handler, resulting in arbitrary command execution or sensitive file access.
The vulnerability mechanism is documented in the GitHub Security Advisory GHSA-fwf6-j56g-m97c. No public proof-of-concept exploit has been released.
Detection Methods for CVE-2026-43941
Indicators of Compromise
- Electerm process spawning unexpected child processes such as cmd.exe, powershell.exe, osascript, or shell interpreters following a terminal session
- Outbound SMB or WebDAV connections originating from the Electerm process to attacker-controlled hosts
- Terminal session logs containing OSC 8 hyperlink escape sequences with non-HTTP schemes such as file://, smb://, or custom protocol handlers
Detection Strategies
- Monitor Electerm process telemetry for atypical child processes or scripting host invocations
- Inspect SSH session recordings and terminal logs for OSC 8 escape sequences (\\x1b]8;;) containing suspicious URL schemes
- Correlate user click events in Electerm with subsequent process creation or network activity on the endpoint
Monitoring Recommendations
- Enable endpoint logging of process creation events with full command lines for all Electerm installations
- Track network connections initiated by Electerm to identify unexpected protocols or destinations
- Audit SSH server endpoints connected to by users running vulnerable Electerm versions
How to Mitigate CVE-2026-43941
Immediate Actions Required
- Restrict Electerm usage to trusted SSH servers and remote hosts until a patch is released
- Advise users to avoid clicking hyperlinks displayed in terminal output, particularly from untrusted sessions
- Disable or remove third-party Electerm plugins from unverified sources
- Inventory all Electerm installations across the organization and identify versions 3.8.15 and prior
Patch Information
No patches are publicly available at the time of publication. Monitor the Electerm GitHub Security Advisory GHSA-fwf6-j56g-m97c for updates. When a fixed release is published, upgrade Electerm on all endpoints to the patched version.
Workarounds
- Configure host-based firewall rules to block outbound SMB and WebDAV traffic from the Electerm process
- Apply operating system controls to disable risky protocol handlers (file, smb, custom application handlers) for the user account running Electerm
- Consider switching to alternative terminal clients for connections to untrusted hosts until a patched release is available
- Train administrators to recognize OSC 8 hyperlink escape sequences in session output and to treat displayed links as untrusted
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
