fix(providers): pin vLLM provider endpoint to validated IP (#5077)

Validate the user-supplied vLLM endpoint (request.azureEndpoint) against
the central SSRF guard and pin the connection to the resolved IP before
issuing any request, mirroring the Azure OpenAI/Anthropic providers. The
operator-configured VLLM_BASE_URL stays trusted and unvalidated.

apps/sim/providers/vllm/index.test.ts

@@ -5,31 +5,50 @@ import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 const {
   mockCreate,
+  openAIArgs,
+  mockOpenAI,
   mockExecuteTool,
   mockPrepareTools,
   mockCheckForced,
   mockCreateStream,
+  mockValidateUrlWithDNS,
+  mockCreatePinnedFetch,
+  pinnedFetchFn,
   envState,
-} = vi.hoisted(() => ({
-  mockCreate: vi.fn(),
-  mockExecuteTool: vi.fn(),
-  mockPrepareTools: vi.fn(),
-  mockCheckForced: vi.fn(),
-  mockCreateStream: vi.fn(),
-  envState: {
-    VLLM_BASE_URL: 'http://localhost:8000',
-    VLLM_API_KEY: undefined as string | undefined,
-  },
-}))
-
-vi.mock('openai', () => ({
-  default: vi.fn().mockImplementation(
-    class {
-      chat = { completions: { create: mockCreate } }
+} = vi.hoisted(() => {
+  const openAIArgs: Array<Record<string, unknown>> = []
+  const mockCreate = vi.fn()
+  const pinnedFetchFn = vi.fn()
+  class MockOpenAI {
+    chat = { completions: { create: mockCreate } }
+    constructor(opts: Record<string, unknown>) {
+      openAIArgs.push(opts)
     }
-  ),
-}))
+  }
+  return {
+    mockCreate,
+    openAIArgs,
+    mockOpenAI: MockOpenAI,
+    mockExecuteTool: vi.fn(),
+    mockPrepareTools: vi.fn(),
+    mockCheckForced: vi.fn(),
+    mockCreateStream: vi.fn(),
+    mockValidateUrlWithDNS: vi.fn(),
+    mockCreatePinnedFetch: vi.fn(() => pinnedFetchFn),
+    pinnedFetchFn,
+    envState: {
+      VLLM_BASE_URL: 'http://localhost:8000',
+      VLLM_API_KEY: undefined as string | undefined,
+    },
+  }
+})
+
+vi.mock('openai', () => ({ default: mockOpenAI }))
 vi.mock('@/lib/core/config/env', () => ({ env: envState }))
+vi.mock('@/lib/core/security/input-validation.server', () => ({
+  validateUrlWithDNS: mockValidateUrlWithDNS,
+  createPinnedFetch: mockCreatePinnedFetch,
+}))
 vi.mock('@/providers', () => ({ MAX_TOOL_ITERATIONS: 20 }))
 vi.mock('@/providers/models', () => ({
   getProviderModels: vi.fn(() => []),
@@ -94,6 +113,7 @@ const createPayload = (callIndex: number) => mockCreate.mock.calls[callIndex][0]
 describe('vllmProvider', () => {
   beforeEach(() => {
     vi.clearAllMocks()
+    openAIArgs.length = 0
     envState.VLLM_BASE_URL = 'http://localhost:8000'
     envState.VLLM_API_KEY = undefined
     mockPrepareTools.mockReturnValue({
@@ -105,6 +125,77 @@ describe('vllmProvider', () => {
     mockCheckForced.mockReturnValue({ hasUsedForcedTool: false, usedForcedTools: [] })
     mockCreateStream.mockReturnValue(new ReadableStream({ start: (c) => c.close() }))
     mockExecuteTool.mockResolvedValue({ success: true, output: { result: 'ok' } })
+    mockValidateUrlWithDNS.mockResolvedValue({ isValid: true, resolvedIP: '203.0.113.10' })
+    mockCreatePinnedFetch.mockReturnValue(pinnedFetchFn)
+  })
+
+  describe('endpoint SSRF protection', () => {
+    it('does not validate or pin when no endpoint is supplied (uses env base URL)', async () => {
+      mockCreate.mockResolvedValueOnce(chatResponse('hi'))
+
+      await vllmProvider.executeRequest({
+        model: 'vllm/llama-3',
+        messages: [{ role: 'user', content: 'hi' }],
+      })
+
+      expect(mockValidateUrlWithDNS).not.toHaveBeenCalled()
+      expect(mockCreatePinnedFetch).not.toHaveBeenCalled()
+      expect(openAIArgs[0].baseURL).toBe('http://localhost:8000/v1')
+      expect(openAIArgs[0].fetch).toBeUndefined()
+    })
+
+    it('validates a user-supplied endpoint and pins the connection to the resolved IP', async () => {
+      mockCreate.mockResolvedValueOnce(chatResponse('hi'))
+
+      await vllmProvider.executeRequest({
+        model: 'vllm/llama-3',
+        messages: [{ role: 'user', content: 'hi' }],
+        azureEndpoint: 'https://my-vllm.example.com',
+      })
+
+      expect(mockValidateUrlWithDNS).toHaveBeenCalledWith(
+        'https://my-vllm.example.com',
+        'vLLM endpoint'
+      )
+      expect(mockCreatePinnedFetch).toHaveBeenCalledWith('203.0.113.10')
+      expect(openAIArgs[0].baseURL).toBe('https://my-vllm.example.com/v1')
+      expect(openAIArgs[0].fetch).toBe(pinnedFetchFn)
+    })
+
+    it('rejects a user-supplied endpoint that fails SSRF validation without issuing a request', async () => {
+      mockValidateUrlWithDNS.mockResolvedValueOnce({
+        isValid: false,
+        error: 'vLLM endpoint resolves to a blocked IP address',
+      })
+
+      await expect(
+        vllmProvider.executeRequest({
+          model: 'vllm/llama-3',
+          messages: [{ role: 'user', content: 'hi' }],
+          azureEndpoint: 'http://169.254.169.254',
+        })
+      ).rejects.toThrow('Invalid vLLM endpoint')
+
+      expect(mockCreatePinnedFetch).not.toHaveBeenCalled()
+      expect(openAIArgs).toHaveLength(0)
+      expect(mockCreate).not.toHaveBeenCalled()
+    })
+
+    it('rejects a validated endpoint that did not resolve to a pinnable IP', async () => {
+      mockValidateUrlWithDNS.mockResolvedValueOnce({ isValid: true })
+
+      await expect(
+        vllmProvider.executeRequest({
+          model: 'vllm/llama-3',
+          messages: [{ role: 'user', content: 'hi' }],
+          azureEndpoint: 'https://my-vllm.example.com',
+        })
+      ).rejects.toThrow('could not resolve a pinnable IP address')
+
+      expect(mockCreatePinnedFetch).not.toHaveBeenCalled()
+      expect(openAIArgs).toHaveLength(0)
+      expect(mockCreate).not.toHaveBeenCalled()
+    })
   })
 
   it('builds a chat payload with the vllm/ prefix stripped and messages assembled in order', async () => {

apps/sim/providers/vllm/index.ts

@@ -3,6 +3,7 @@ import { getErrorMessage, toError } from '@sim/utils/errors'
 import OpenAI from 'openai'
 import type { ChatCompletionCreateParamsStreaming } from 'openai/resources/chat/completions'
 import { env } from '@/lib/core/config/env'
+import { createPinnedFetch, validateUrlWithDNS } from '@/lib/core/security/input-validation.server'
 import type { StreamingExecution } from '@/executor/types'
 import { MAX_TOOL_ITERATIONS } from '@/providers'
 import { formatMessagesForProvider } from '@/providers/attachments'
@@ -95,15 +96,40 @@ export const vllmProvider: ProviderConfig = {
       stream: !!request.stream,
     })
 
-    const baseUrl = (request.azureEndpoint || env.VLLM_BASE_URL || '').replace(/\/$/, '')
+    const userProvidedEndpoint = request.azureEndpoint
+
+    const baseUrl = (userProvidedEndpoint || env.VLLM_BASE_URL || '').replace(/\/$/, '')
     if (!baseUrl) {
       throw new Error('VLLM_BASE_URL is required for vLLM provider')
     }
 
+    /**
+     * A user-supplied endpoint is attacker-controlled: validate it against the
+     * central SSRF guard and pin the connection to the resolved IP to defeat DNS
+     * rebinding. The operator-configured `VLLM_BASE_URL` is trusted and left
+     * unvalidated, mirroring the Azure providers.
+     */
+    let pinnedFetch: typeof fetch | undefined
+    if (userProvidedEndpoint) {
+      const validation = await validateUrlWithDNS(userProvidedEndpoint, 'vLLM endpoint')
+      if (!validation.isValid) {
+        logger.warn('Blocked SSRF attempt via vLLM endpoint', {
+          endpoint: userProvidedEndpoint,
+          error: validation.error,
+        })
+        throw new Error(`Invalid vLLM endpoint: ${validation.error}`)
+      }
+      if (!validation.resolvedIP) {
+        throw new Error('Invalid vLLM endpoint: could not resolve a pinnable IP address')
+      }
+      pinnedFetch = createPinnedFetch(validation.resolvedIP)
+    }
+
     const apiKey = request.apiKey || env.VLLM_API_KEY || 'empty'
     const vllm = new OpenAI({
       apiKey,
       baseURL: `${baseUrl}/v1`,
+      ...(pinnedFetch ? { fetch: pinnedFetch } : {}),
     })
 
     const allMessages: Message[] = []