Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization_CVE-2026-42581

5.8 / 10

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Description

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent for HTTP/1.0. An attacker that sends an HTTP/1.0 request with both headers causes Netty to decode the body as chunked while leaving Content-Length intact in the forwarded HttpMessage. Any downstream proxy or handler that trusts Content-Length over Transfer-Encoding will disagree on message boundaries, enabling request smuggling. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Basic Information

ID CVE-2026-42581

Source GitHub_M

Published May 13, 2026 at 17:54

Modified May 13, 2026 at 18:42

Affected Product

Vendor netty

Product netty

Version >= 4.2.0.Alpha1, < 4.2.13.Final

Affected Versions netty netty >= 4.2.0.Alpha1, < 4.2.13.Final
netty netty < 4.1.133.Final

CWE Classification

CWE-444

References

github.com /netty/netty/security/advisories/GHSA-xxqh-mfjm-7mv9

{
    "lastseen": "",
    "description": "Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent for HTTP/1.0. An attacker that sends an HTTP/1.0 request with both headers causes Netty to decode the body as chunked while leaving Content-Length intact in the forwarded HttpMessage. Any downstream proxy or handler that trusts Content-Length over Transfer-Encoding will disagree on message boundaries, enabling request smuggling. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.",
    "published": "2026-05-13T17:54:44.492Z",
    "modified": "2026-05-13T18:42:59.711Z",
    "type": "cve",
    "title": "Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization",
    "source": "GitHub_M",
    "references": "https://github.com/netty/netty/security/advisories/GHSA-xxqh-mfjm-7mv9",
    "id": "CVE-2026-42581",
    "bulletinFamily": "",
    "cwe": [
        "CWE-444"
    ],
    "cvelist": null,
    "sourceData": "netty netty >= 4.2.0.Alpha1, < 4.2.13.Final\nnetty netty < 4.1.133.Final",
    "sourceHref": "",
    "cvss": {
        "score": 5.8,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "netty",
    "version": ">= 4.2.0.Alpha1, < 4.2.13.Final",
    "vendor": "netty",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}