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Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder

Type: advisorySources: OSV

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, HttpPostRequestEncoder constructs multipart HTTP request bodies by directly concatenating user-supplied filenames and field names into Content-Disposition MIME headers without validating or sanitizing CRLF characters (\r\n). Since MIME headers are delimited by CRLF, an attacker who controls the filename can inject arbitrary MIME headers into the multipart body part. The root cause is that neither the encoder nor the FileUpload implementations' setFilename() methods, which only check for null, neutralize CRLF characters before the filename is embedded into the header. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-59921
Confirmed fixed CVEs
Not specified
Updated in this feed
8 Nov 2026, 00:51 UTC · Revision 1

Source evidence

Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder

core-osv · Original source

Published 28 Jul 2026, 22:28 UTC

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, HttpPostRequestEncoder constructs multipart HTTP request bodies by directly concatenating user-supplied filenames and field names into Content-Disposition MIME headers without validating or sanitizing CRLF characters (\r\n). Since MIME headers are delimited by CRLF, an attacker who controls the filename can inject arbitrary MIME headers into the multipart body part. The root cause is that neither the encoder nor the FileUpload implementations' setFilename() methods, which only check for null, neutralize CRLF characters before the filename is embedded into the header. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

osv:CVE-2026-59921
Complete source record
{
  "id": "1d5133f3c97625c3b2d66a669dcac73c4cc12876816ead828788815c7dae76a1",
  "url": "https://osv.dev/vulnerability/CVE-2026-59921",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder",
    "summary": "Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, HttpPostRequestEncoder constructs multipart HTTP request bodies by directly concatenating user-supplied filenames and field names into Content-Disposition MIME headers without validating or sanitizing CRLF characters (\\r\\n). Since MIME headers are delimited by CRLF, an attacker who controls the filename can inject arbitrary MIME headers into the multipart body part. The root cause is that neither the encoder nor the FileUpload implementations' setFilename() methods, which only check for null, neutralize CRLF characters before the filename is embedded into the header. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.",
    "evidence": "osv:CVE-2026-59921",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-59921",
      "aliases": [
        "CVE-2026-59921",
        "GHSA-gcjf-9mgh-3p7g"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/netty/netty",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "fca0764703b3bb59c6e6dc5d29c6d9710d35c0e6"
                },
                {
                  "introduced": "09e64d259c99be8b5b2a471a78f11e65eb82598a"
                },
                {
                  "fixed": "3703d79669ee024f6483c9d8697ac58ba546df33"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.1.136"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "4.2.0"
                      },
                      {
                        "fixed": "4.2.16"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
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            "netty-4.2.11.Final",
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            "netty-4.2.10.Final",
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            "netty-4.2.5.Final",
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            "netty-4.1.124.Final",
            "netty-4.1.123.Final",
            "netty-4.2.3.Final",
            "netty-4.2.2.Final",
            "netty-4.1.122.Final",
            "netty-4.2.1.Final",
            "netty-4.1.121.Final",
            "netty-4.1.120.Final",
            "netty-4.2.0.Final",
            "netty-4.1.119.Final",
            "netty-4.1.118.Final",
            "netty-4.1.117.Final",
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            "netty-4.1.47.Final",
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            "netty-4.1.45.Final",
            "netty-4.1.44.Final",
            "netty-4.1.43.Final",
            "netty-4.1.42.Final",
            "netty-4.1.41.Final",
            "netty-4.1.40.Final",
            "netty-4.1.39.Final",
            "netty-4.1.38.Final",
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            "netty-4.1.36.Final",
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            "netty-4.1.28.Final",
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            "netty-4.1.25.Final",
            "netty-4.1.24.Final",
            "netty-4.1.23.Final",
            "netty-4.1.22.Final",
            "netty-4.1.21.Final",
            "netty-4.1.20.Final",
            "netty-4.1.19.Final",
            "netty-4.1.18.Final",
            "netty-4.1.17.Final",
            "netty-4.1.16.Final",
            "netty-4.1.15.Final",
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            "netty-4.1.10.Final",
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            "netty-4.1.1.Final",
            "netty-4.1.0.Final",
            "netty-4.1.0.CR7",
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            "netty-4.1.0.CR5",
            "netty-4.1.0.CR4",
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            "netty-4.1.0.CR1",
            "netty-4.1.0.Beta8",
            "netty-4.1.0.Beta7",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59921.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:52.514566251Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59921.json",
        "https://github.com/netty/netty/security/advisories/GHSA-gcjf-9mgh-3p7g",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-59921"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-93"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59921.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-59921",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 521112,
  "published_at": "2026-07-28T22:28:51.267+00:00"
}