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 in the HttpClientCodec component. An attacker can cause response desynchronization and potentially compromise the integrity and availability of HTTP parsing by sending crafted HTTP/1.1 pipelined requests that include a HEAD request and trigger the server to send 1xx responses. This can result in unsafe reuse of the socket and misinterpretation of response bodies.

Note:

This is only exploitable if HTTP/1.1 pipelining is used, a HEAD request is present in the pipeline, and the server sends 1xx responses.

    @Test
    public void test() {
        EmbeddedChannel channel = new EmbeddedChannel(new HttpClientCodec());

        assertTrue(channel.writeOutbound(new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET, "/1")));
        ByteBuf request = channel.readOutbound();
        request.release();
        assertNull(channel.readOutbound());

        assertTrue(channel.writeOutbound(new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.HEAD, "/2")));
        request = channel.readOutbound();
        request.release();
        assertNull(channel.readOutbound());

        String responseStr = "HTTP/1.1 103 Early Hints\r\n\r\n" +
                "HTTP/1.1 200 OK\r\nContent-Length: 5\r\n\r\nhello" +
                "HTTP/1.1 200 OK\r\n\r\n";
        assertTrue(channel.writeInbound(Unpooled.copiedBuffer(responseStr, CharsetUtil.US_ASCII)));

        // Response 1
        HttpResponse response = channel.readInbound();
        assertEquals(HttpResponseStatus.EARLY_HINTS, response.status());
        LastHttpContent last = channel.readInbound();
        assertEquals(0, last.content().readableBytes());
        last.release();

        // Response 2
        response = channel.readInbound();
        assertEquals(HttpResponseStatus.OK, response.status());
        last = channel.readInbound();
        assertEquals(0, last.content().readableBytes());
        last.release();

        // Response 3
        FullHttpResponse response1 = channel.readInbound();
        assertTrue(response1.decoderResult().isFailure());
        assertEquals(0, response1.content().readableBytes());
        response1.release();

        assertFalse(channel.finish());
    }

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