9.2

CVSS Score

4.0

-

CVSS Score

Basic Information

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CVE-2026-59800

CVE-2026-59800: 9Router < 0.4.44 - OS Command Injection via sudoPassword Parameter in Tailscale Install Endpoint

9Router before 0.4.44 contains an OS command injection vulnerability in the unauthenticated POST /api/tunnel/tailscale-install endpoint (this route is not covered by the dashboard middleware matcher, so no authorization check is applied). The sudoPassword field from the request body is written to the stdin of a 'sudo -S sh' child process. When sudo does not prompt for a password (the process runs as root, NOPASSWD is configured, or a recent sudo timestamp cache exists), the sudoPassword value is interpreted by sh as a shell command, allowing a remote unauthenticated attacker to execute arbitrary OS commands. Exploitation evidence was first observed by the Shadowserver Foundation on 2026-07-04 (UTC).

(GitHub Advisory)

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CVE-2026-59800

CVE-2026-59800:

9.2

CVSS Score

4.0

-

CVSS Score

Basic Information

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Technical Details

SSVC / BOD 26-04 ↗

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Package Name	Ecosystem	Vulnerable Versions	First Patched Version
9router	npm	< 0.4.44	0.4.44

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability is a combination of missing authorization and an OS command injection. The analysis began by examining the provided vulnerability description, which clearly outlined the vulnerable code paths. The POST handler in src/app/api/tunnel/tailscale-install/route.js was identified as the unauthenticated entry point. The description also pointed to installTailscaleLinux in src/lib/tunnel/tailscale.js as the function where the command injection occurs.

To confirm this and gather evidence, I analyzed the commits between the last vulnerable version (v0.4.39) and the first patched version (v0.4.44). The commit a28c5ec98b58d685b9855bf429f07d780312c8f6 contained the security fixes.

The patch analysis revealed two key changes:

Authorization Fix: The middleware configuration in src/proxy.js and src/dashboardGuard.js was updated to include /api/tunnel/* paths, thereby placing the vulnerable endpoint behind an authentication and authorization check.
Command Injection Fix: The installTailscaleLinux function was rewritten to avoid piping user input directly into a shell. The new implementation writes the downloaded installation script to a temporary file and executes it by its path, while also adding a check to reject passwords containing newlines. The attacker-controlled sudoPassword is still written to stdin for sudo, but the sh process no longer reads from it, mitigating the injection vector.

Based on this evidence, the POST route handler and the installTailscaleLinux function are the two primary functions that would appear in a runtime profile during exploitation.

Vulnerable functions

POST

src/app/api/tunnel/tailscale-install/route.js

This function is the unauthenticated API route handler for `POST /api/tunnel/tailscale-install`. It directly receives the attacker-controlled `sudoPassword` from the request body and passes it down to the vulnerable installation function. The lack of authorization on this route is the primary reason the vulnerability is remotely exploitable without authentication.

installTailscaleLinux

src/lib/tunnel/tailscale.js

This function contains the core OS command injection vulnerability. It takes the `sudoPassword` and writes it directly to the standard input of a `sudo -S sh` process. In scenarios where the application is running as root or with passwordless sudo, the `sh` shell interprets this input as a command to be executed, allowing an attacker to run arbitrary commands on the host system.

Vulnerability Intelligence
Miggo AI

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WAF Rule

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Reasoning

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