Hardcoded CORS wildcard on TTS endpoint enables cross-origin credential abuse from any webpage

packages/server/src/controllers/text-to-speech/index.ts

@@ -89,8 +89,6 @@ const generateTextToSpeech = async (req: Request, res: Response) => {
         res.setHeader('Content-Type', 'text/event-stream')
         res.setHeader('Cache-Control', 'no-cache')
         res.setHeader('Connection', 'keep-alive')
-        res.setHeader('Access-Control-Allow-Origin', '*')
-        res.setHeader('Access-Control-Allow-Headers', 'Cache-Control')
 
         const appServer = getRunningExpressApp()
         const options = {

packages/server/src/utils/XSS.ts

@@ -1,6 +1,6 @@
 import { Request, Response, NextFunction } from 'express'
 import sanitizeHtml from 'sanitize-html'
-import { extractChatflowId, validateChatflowDomain, isPublicChatflowRequest } from './domainValidation'
+import { extractChatflowId, validateChatflowDomain, isPublicChatflowRequest, isTTSGenerateRequest } from './domainValidation'
 
 export function sanitizeMiddleware(req: Request, res: Response, next: NextFunction): void {
     // decoding is necessary as the url is encoded by the browser
@@ -44,6 +44,7 @@ export function getCorsOptions(): any {
             origin: async (origin: string | undefined, originCallback: (err: Error | null, allow?: boolean) => void) => {
                 const allowedOrigins = getAllowedCorsOrigins()
                 const isPublicChatflowReq = isPublicChatflowRequest(req.url)
+                const isTTSReq = isTTSGenerateRequest(req.url)
                 const allowedList = parseAllowedOrigins(allowedOrigins)
                 const originLc = origin?.toLowerCase()
 
@@ -53,9 +54,10 @@ export function getCorsOptions(): any {
                 // Global allow: '*' or exact match
                 const globallyAllowed = allowedOrigins === '*' || allowedList.includes(originLc)
 
-                if (isPublicChatflowReq) {
+                if (isPublicChatflowReq || isTTSReq) {
                     // Per-chatflow allowlist OR globally allowed
-                    const chatflowId = extractChatflowId(req.url)
+                    // TTS generate passes chatflowId in the request body, not the URL path
+                    const chatflowId = isTTSReq ? req.body?.chatflowId : extractChatflowId(req.url)
                     let chatflowAllowed = false
                     if (chatflowId) {
                         try {
@@ -65,6 +67,9 @@ export function getCorsOptions(): any {
                             console.error('Domain validation error:', error)
                             chatflowAllowed = false
                         }
+                    } else if (isTTSReq) {
+                        // OPTIONS preflight has no body — allow it through so the actual POST can be validated with chatflowId
+                        chatflowAllowed = true
                     }
                     return originCallback(null, globallyAllowed || chatflowAllowed)
                 }

packages/server/src/utils/domainValidation.ts

@@ -9,6 +9,9 @@ import logger from './logger'
 // /chatflows-streaming/{chatflowId}
 const ALLOWED_SLUGS = ['/prediction/', '/public-chatbotConfig/', '/chatflows-streaming/']
 
+// The TTS generate endpoint passes chatflowId in the request body, not the URL path
+const TTS_GENERATE_PATH = '/api/v1/text-to-speech/generate'
+
 /**
  * Validates if the origin is allowed for a specific chatflow
  * @param chatflowId - The chatflow ID to validate against
@@ -105,6 +108,16 @@ function isPublicChatflowRequest(url: string): boolean {
     return extractSlugFromUrl(url) !== null
 }
 
+/**
+ * Checks if the request is for the TTS generate endpoint.
+ * This endpoint passes chatflowId in the request body rather than the URL path.
+ * @param url - The request URL
+ * @returns boolean - True if it's the TTS generate endpoint
+ */
+function isTTSGenerateRequest(url: string): boolean {
+    return url.split('?')[0] === TTS_GENERATE_PATH
+}
+
 /**
  * Get the custom error message for unauthorized origin
  * @param chatflowId - The chatflow ID
@@ -129,4 +142,4 @@ async function getUnauthorizedOriginError(chatflowId: string, workspaceId?: stri
     }
 }
 
-export { isPublicChatflowRequest, extractChatflowId, validateChatflowDomain, getUnauthorizedOriginError }
+export { isPublicChatflowRequest, isTTSGenerateRequest, extractChatflowId, validateChatflowDomain, getUnauthorizedOriginError }