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CVE-2026-42581

📛 CVE Title

Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization

⬇ Download JSON ⚠ View as Threat

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.

Overview

State
PUBLISHED
Assigner (CNA)
GitHub_M
CVSS severity
MEDIUM
CVSS score
CVSS 5.8 / 10 5.8 5.8 / 10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Effective score
5.8 / 10 MEDIUM source: CNA overview
CWE(s)
CWE-444
Reserved
2026-04-28
Published
2026-05-13 19:54 UTC
Last updated
2026-05-13 20:42 UTC
Source
https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/42xxx/CVE-2026-42581.json
Linked Threat
CVE-2026-42581 — CVE-2026-42581

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published
2026-05-13 19:17:23 UTC
NVD last modified
2026-05-18 13:14:18 UTC
NVD CVSS v3.1
CVSS 5.8 / 10 5.8 5.8 / 10 MEDIUM source: security-advisories@github.com
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Exploitability subscore
3.9 / 10
Impact subscore
1.4 / 10
EPSS score
0.0002 (probability of exploitation in next 30 days)
EPSS percentile
4.57% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

NVD / KEV / EPSS data refreshed 2026-05-25 09:36 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID
EUVD-2026-30124
Assigner
GitHub_M
Published
May 13, 2026, 5:54:44 PM
Updated
May 13, 2026, 6:42:59 PM
EUVD base score (CVSS 3.1)
5.8 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
EUVD-reported EPSS
0.0200
Vendors
netty
Products
netty (< 4.1.133.Final)
netty (4.2.0.Alpha1, < 4.2.13.Final)
Aliases
GHSA-xxqh-mfjm-7mv9

ENISA 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.

EUVD references (1)

Affected products (1)
VendorProductVersionsPlatforms
netty netty >= 4.2.0.Alpha1, < 4.2.13.Final (affected), < 4.1.133.Final (affected) —

Affected products — CPE 2.3 (1) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

  • cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*

Vendor references (1)

References embedded in the original CVE record by the assigning CNA.

MITRE references (1) cveawg.mitre.org

Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.

Web references (3)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

NVD-tagged references (2)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

Remediations (18)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-42581.json.

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-42581",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-13T18:42:38.397208Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-13T18:42:59.711Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/netty/netty/security/advisories/GHSA-xxqh-mfjm-7mv9"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "netty",
          "vendor": "netty",
          "versions": [
            {
              "status": "affected",
              "version": ">= 4.2.0.Alpha1, < 4.2.13.Final"
            },
            {
              "status": "affected",
              "version": "< 4.1.133.Final"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.8,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-444",
              "description": "CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-13T17:54:44.492Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/netty/netty/security/advisories/GHSA-xxqh-mfjm-7mv9",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/netty/netty/security/advisories/GHSA-xxqh-mfjm-7mv9"
        }
      ],
      "source": {
        "advisory": "GHSA-xxqh-mfjm-7mv9",
        "discovery": "UNKNOWN"
      },
      "title": "Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-42581",
    "datePublished": "2026-05-13T17:54:44.492Z",
    "dateReserved": "2026-04-28T17:26:12.085Z",
    "dateUpdated": "2026-05-13T18:42:59.711Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}