Electerm — CraftedSignal Threat Feed

Electerm Arbitrary Code Execution via Crafted URI or CLI Arguments

hello@craftedsignal.io — Fri, 08 May 2026 18:46:04 +0000

Electerm, a free and open-source terminal/ssh/sftp client, is vulnerable to arbitrary code execution. Versions 3.0.6 through 3.8.14 are susceptible to this vulnerability. An attacker can exploit this by crafting a malicious electerm:// URI or by crafting a shortcut/command that launches electerm with attacker-controlled --opts arguments. Successful exploitation requires a user to click the malicious link or open the malicious shortcut file. This vulnerability allows attackers to execute arbitrary code on the victim’s machine, potentially leading to system compromise, data theft, or other malicious activities. The vulnerability was reported by Curly-Haired-Baboon.

Attack Chain

The attacker crafts a malicious electerm:// URI or a shortcut/command containing malicious --opts arguments.
The attacker distributes the malicious URI or shortcut/command to the victim via social engineering or other means.
The victim clicks on the malicious electerm:// URI or opens the malicious shortcut/command.
Electerm is launched with the attacker-controlled parameters.
Due to insufficient validation of the input, the attacker’s payload is processed by Electerm.
The attacker’s payload executes arbitrary code on the victim’s machine.
The attacker gains control of the compromised system, enabling them to perform malicious activities.

Impact

Successful exploitation of this vulnerability can lead to arbitrary code execution on the victim’s machine. This can result in a wide range of malicious activities, including but not limited to, system compromise, data theft, installation of malware, and denial of service. Given the nature of Electerm as a terminal client, attackers could potentially gain access to sensitive credentials and systems managed through the application.

Recommendation

Upgrade Electerm to version 3.8.15 or later to patch CVE-2026-43944.
Disable or unregister electerm protocol handlers (Deep Link settings) as a workaround.
Avoid clicking electerm:// links from untrusted sources.
Refrain from running electerm with untrusted --opts arguments or opening .lnk / .desktop files from untrusted sources.
Deploy the Sigma rule “Detect Electerm URI Protocol Handler Abuse” to identify attempts to exploit this vulnerability by monitoring process execution that involves the electerm protocol.

Electerm Remote Code Execution Vulnerability via Malicious Filenames

hello@craftedsignal.io — Fri, 08 May 2026 18:43:52 +0000

Electerm, a terminal/ssh/sftp client, is vulnerable to a remote code execution (RCE) attack (CVE-2026-43943) when using the “open with system editor” or “Edit with custom editor” feature. This vulnerability affects versions 3.7.8 and earlier. A malicious actor who controls the SSH server or has the ability to manipulate filenames can inject shell metacharacters into a filename. When a user attempts to open the file with the vulnerable feature, Electerm passes the filename directly to the command line without sanitization, leading to command execution with the user’s privileges. This allows the attacker to potentially run arbitrary code, install malware, or move laterally within the network. The vulnerability was patched in version 3.7.9.

Attack Chain

Attacker compromises or sets up a malicious SSH server.
Attacker creates a file with a specially crafted filename containing shell metacharacters (e.g., evil; rm -rf /tmp; touch /tmp/pwned).
Victim connects to the malicious SSH server using Electerm.
Victim browses the SFTP file system and sees the attacker-controlled filename.
Victim selects the malicious file and chooses the “open with system editor” or “Edit with custom editor” option.
Electerm executes a command to open the file, passing the malicious filename unsanitized to the system shell (e.g., xdg-open "evil; rm -rf /tmp; touch /tmp/pwned").
The shell executes the injected commands, deleting files in /tmp and creating a file named /tmp/pwned in this example.
Attacker achieves arbitrary code execution on the victim’s machine with the user’s privileges.

Impact

Successful exploitation of this vulnerability allows a malicious actor to execute arbitrary code on the victim’s machine. This could lead to a variety of malicious outcomes, including malware installation, data theft, or lateral movement within the victim’s network. The number of potential victims is limited to Electerm users who connect to untrusted SSH servers and use the vulnerable “open with system editor” or “Edit with custom editor” features. This vulnerability could have significant impact for developers and system administrators who rely on Electerm for remote server management.

Recommendation

Upgrade Electerm to version 3.7.9 or later to patch CVE-2026-43943.
Deploy the Sigma rule Detect Electerm RCE via Filename to detect exploitation attempts.
Until a patch can be applied, refrain from using the “open with system editor” or “Edit with custom editor” feature when connected to untrusted SSH servers, as recommended in the advisory.
If the “open with system editor” feature must be used, ensure connections are exclusively established with trusted servers and perform rigorous filename validation before editing.

Electerm Arbitrary Protocol Execution Vulnerability

hello@craftedsignal.io — Wed, 03 Jul 2024 12:00:00 +0000

Electerm, a cross-platform terminal application, is vulnerable to an arbitrary protocol execution vulnerability (CVE-2026-43941) in versions 3.8.15 and earlier. This flaw stems from the application’s failure to properly validate URLs passed to the shell.openExternal function. An attacker who can control terminal output, such as through a compromised SSH server or a malicious plugin, can inject a crafted URI into the terminal. If a user clicks on this malicious link, Electerm will execute it using the operating system’s default protocol handler, potentially leading to code execution, data exfiltration, or other malicious activities. This vulnerability requires user interaction (clicking the link) to be exploited.

Attack Chain

Attacker compromises a remote SSH server or injects malicious content into terminal output.
The attacker crafts a malicious URI containing a dangerous protocol handler like ms-msdt:, search-ms:, or file://.
The malicious URI is printed to the Electerm terminal connected to the compromised SSH server.
The victim, using Electerm, views the terminal output containing the malicious URI.
The victim clicks on the malicious URI hyperlink in the Electerm terminal.
Electerm’s shell.openExternal function executes the URI without proper validation.
The operating system’s default protocol handler is invoked, executing the attacker’s payload (e.g., code execution via ms-msdt:, NTLM hash leak via file://).
Attacker achieves arbitrary code execution or exfiltrates sensitive information.

Impact

Successful exploitation of this vulnerability (CVE-2026-43941) could allow an attacker to execute arbitrary code on a victim’s machine. This could lead to complete system compromise, data theft, or the installation of malware. The vulnerability affects all Electerm users who interact with untrusted terminal outputs. The number of potential victims is dependent on Electerm’s user base. If successfully exploited, an attacker gains the privileges of the user running Electerm.

Recommendation

Deploy the Sigma rule “Detect Electerm Suspicious URI Invocation” to detect attempts to exploit CVE-2026-43941 by monitoring process creations with unusual protocol handlers (see rule definition below).
Apply the workaround to disable hyperlink rendering in electerm’s terminal settings until a patch is available.
Monitor the electerm GitHub releases and security page for an update addressing this issue.

Electerm Path Traversal Vulnerability Leads to Arbitrary Code Execution

hello@craftedsignal.io — Thu, 09 May 2024 12:00:00 +0000

Electerm versions before 3.7.16 are susceptible to a critical path traversal vulnerability within the runWidget function located in src/app/widgets/load-widget.js. This function insecurely constructs file paths by concatenating user-supplied widget identifiers without proper sanitization. Successful exploitation of CVE-2026-43940 allows an attacker with JavaScript execution within the renderer process to load and execute arbitrary JavaScript files anywhere on the victim’s filesystem. This results in local code execution with the full privileges of the Electerm process, potentially leading to complete system compromise on Windows 10 and Linux systems. The vulnerability was confirmed on v3.7.9, Win10.

Attack Chain

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