CVE-2026-7039: tufantunc ssh-mcp RCE Vulnerability

CVE-2026-7039 Overview

A command injection vulnerability has been identified in tufantunc ssh-mcp up to version 1.5.0. The vulnerability exists in the shell.write function within the src/index.ts file. Attackers with local access can exploit this flaw by manipulating the Description argument, leading to arbitrary command injection on the target system. The exploit has been publicly disclosed, and the project maintainer has been notified through an issue report but has not yet responded.

Critical Impact

Local attackers can execute arbitrary commands on systems running vulnerable versions of ssh-mcp by injecting malicious input through the Description parameter, potentially leading to complete system compromise.

Affected Products

• tufantunc ssh-mcp versions up to and including 1.5.0

Discovery Timeline

• 2026-04-26 - CVE-2026-7039 published to NVD
• 2026-04-29 - Last updated in NVD database

Technical Details for CVE-2026-7039

Vulnerability Analysis

This vulnerability is classified as CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), commonly known as injection. The shell.write function in src/index.ts fails to properly sanitize user-supplied input from the Description argument before passing it to shell execution contexts. This allows an attacker to craft malicious input containing shell metacharacters or command sequences that escape the intended context and execute arbitrary commands.

The local attack vector means an attacker must already have some level of access to the system where ssh-mcp is running. However, once this access is established, the vulnerability allows for significant privilege escalation and lateral movement capabilities. The impact extends to confidentiality, integrity, and availability of the affected system, as arbitrary command execution can lead to data theft, system modification, or denial of service.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and sanitization within the shell.write function. When processing the Description argument, the application fails to escape or filter shell metacharacters such as ;, |, &, $(), and backticks. This allows specially crafted input to break out of the intended command context and execute additional attacker-controlled commands.

The vulnerable code path accepts user input and passes it directly to shell execution without implementing proper parameterization or input validation mechanisms. This is a common pattern in applications that interact with system shells without adequate security controls.

Attack Vector

The attack requires local access to the system running the vulnerable ssh-mcp component. An attacker can exploit this vulnerability by providing malicious input in the Description field that contains shell command injection sequences. When the shell.write function processes this input, the injected commands are executed with the privileges of the ssh-mcp process.

Typical exploitation involves:

1. Identifying an input vector that reaches the vulnerable shell.write function
2. Crafting a payload that includes shell metacharacters to escape the intended context
3. Injecting commands that achieve the attacker's objectives (data exfiltration, persistence, lateral movement)

For detailed technical information about this vulnerability, refer to the GitHub Issue Discussion and the VulDB entry.

Detection Methods for CVE-2026-7039

Indicators of Compromise

• Unusual command execution patterns originating from ssh-mcp processes
• Unexpected child processes spawned by the ssh-mcp application
• Anomalous system calls or shell invocations containing suspicious metacharacters
• Log entries showing malformed or suspicious Description field values

Detection Strategies

• Monitor process execution chains for ssh-mcp spawning unexpected child processes
• Implement application-level logging to capture all input processed by the shell.write function
• Use endpoint detection tools to identify command injection patterns in process arguments
• Review system logs for evidence of shell metacharacter sequences in ssh-mcp related entries

Monitoring Recommendations

• Enable comprehensive logging for all ssh-mcp operations
• Configure alerting for any command execution anomalies from ssh-mcp processes
• Implement file integrity monitoring on critical system files that could be modified post-exploitation
• Deploy behavioral analysis to detect deviations from normal ssh-mcp operation patterns

How to Mitigate CVE-2026-7039

Immediate Actions Required

• Audit systems to identify all instances of ssh-mcp version 1.5.0 or earlier
• Restrict local access to systems running vulnerable ssh-mcp installations
• Implement additional input validation at the application boundary if possible
• Consider removing or disabling ssh-mcp until a patched version becomes available

Patch Information

At the time of publication, no official patch has been released by the project maintainer. The vulnerability was reported through a GitHub issue, but the project has not responded. Users should monitor the ssh-mcp repository for updates and consider alternative solutions if the vulnerability remains unaddressed.

Workarounds

• Limit local access to systems running ssh-mcp to trusted users only
• Implement network segmentation to isolate systems running vulnerable components
• Apply application-level input filtering to sanitize Description field values before they reach ssh-mcp
• Consider using alternative SSH management tools that do not exhibit this vulnerability
• Deploy endpoint protection solutions capable of detecting command injection attempts