Executive Summary

CVE-2026-43943 is a remote code execution vulnerability in the electerm application, specifically in its SFTP feature's "open with system editor" or "Edit with custom editor" functionality. Before version 3.7.9, when a user tries to edit a file using these features, the filename is passed directly to the command line without proper sanitization.

An attacker who controls the SSH server or the user's operating system can craft a malicious filename containing shell metacharacters. When the victim attempts to edit this file, the injected commands execute on their machine with the user's privileges, allowing the attacker to run arbitrary code.

This vulnerability arises from unsafe string interpolation in the code that handles file opening, enabling command injection attacks. The issue was fixed by changing the method to safely pass filenames as literal strings or properly escaped arguments.

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Impact Analysis

If exploited, this vulnerability allows an attacker to execute arbitrary code on your machine with your user privileges. This can lead to malware installation, unauthorized access, or lateral movement within your network.

Because the attack requires only that a user open a maliciously named file using the vulnerable feature, it can be triggered with low complexity and no prior privileges.

The impacts include potential compromise of confidentiality, integrity, and availability of your system and data.

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Detection Guidance

This vulnerability involves command injection through filenames when using electerm's SFTP feature to open files with a system or custom editor. Detection involves identifying if filenames with shell metacharacters are being passed unsanitized to system commands.

To detect exploitation attempts or presence of malicious filenames, you can monitor logs or SFTP sessions for filenames containing suspicious shell metacharacters such as semicolons (;), backticks (`), dollar signs ($), or quotes (" or ').

Since the vulnerability triggers when editing files with system or custom editors, you can also check for processes spawned by electerm that include suspicious command line arguments.

Suggested commands to help detect potential exploitation attempts include:

• On Unix-like systems, use process monitoring to find electerm editor commands with suspicious arguments, e.g.:
• ps aux | grep -E 'electerm.*(\;|`|\$|"|\')'
• Search SFTP server logs or electerm logs for filenames containing shell metacharacters:
• grep -E '(;|`|\$|"|\')' /path/to/sftp/logs/*
• Monitor network traffic for suspicious command injection patterns if possible.

Note that no specific detection commands are provided in the resources, so these suggestions are based on the nature of the vulnerability and typical detection methods for command injection.

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Mitigation Strategies

The primary mitigation is to upgrade electerm to version 3.7.9 or later, where the vulnerability has been patched by properly sanitizing filenames before passing them to system commands.

Until you can upgrade, avoid using the 'open with system editor' or 'Edit with custom editor' features on files received from untrusted SSH servers or sources.

Use the built-in editor in electerm instead of external editors to reduce risk.

Ensure that connections are only made to trusted SSH servers and validate filenames rigorously before opening or editing.

Consider monitoring for suspicious filenames containing shell metacharacters and restrict or sanitize them if possible.

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Compliance Impact

CVE-2026-43943 is a high-severity remote code execution vulnerability that allows an attacker to execute arbitrary code with the user's privileges by exploiting unsanitized filenames in electerm's SFTP editing features.

Such unauthorized code execution and potential malware installation or lateral movement within a network can lead to breaches of confidentiality, integrity, and availability of sensitive data.

This can impact compliance with common standards and regulations like GDPR and HIPAA, which require protection of personal and sensitive data against unauthorized access and compromise.

If exploited, this vulnerability could result in unauthorized data disclosure or alteration, violating data protection requirements and potentially leading to regulatory penalties.

Mitigation involves applying the patch in version 3.7.9 and avoiding use of vulnerable features with untrusted servers, which helps maintain compliance by reducing risk of exploitation.

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