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netty — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2021-43797

Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. Netty prior to version 4.1.71.Final skips control chars when they are present at the beginning / end of the header name. It should instead fail fast as these are not allowed by the spec and could lead to HTTP request smuggling. Failing to do the validation might cause netty to "sanitize" header names before it forward these to another remote system when used as proxy. This remote system can't see the invalid usage anymore, and therefore does not do the validation itself. Users should upgrade to version 4.1.71.Final.

Products
netty
Affected versions
Not specified
Fixed versions
1:4.1.48-6
CVEs
CVE-2021-43797
Confirmed fixed CVEs
Not specified
Updated in this feed
28 Oct 2026, 11:06 UTC · Revision 1

Source evidence

DEBIAN-CVE-2021-43797

core-osv · Original source

Published 9 Dec 2021, 19:15 UTC

Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. Netty prior to version 4.1.71.Final skips control chars when they are present at the beginning / end of the header name. It should instead fail fast as these are not allowed by the spec and could lead to HTTP request smuggling. Failing to do the validation might cause netty to "sanitize" header names before it forward these to another remote system when used as proxy. This remote system can't see the invalid usage anymore, and therefore does not do the validation itself. Users should upgrade to version 4.1.71.Final.

osv:DEBIAN-CVE-2021-43797

netty

Fixed versions: 1:4.1.48-6

netty

Fixed versions: 1:4.1.48-6

netty

Fixed versions: 1:4.1.48-6

Complete source record
{
  "id": "eb6b83948668691748c9e5a9847180ab4e7d06498a0f16569065ed4335461161",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-43797",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2021-43797",
    "summary": "Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. Netty prior to version 4.1.71.Final skips control chars when they are present at the beginning / end of the header name. It should instead fail fast as these are not allowed by the spec and could lead to HTTP request smuggling. Failing to do the validation might cause netty to \"sanitize\" header names before it forward these to another remote system when used as proxy. This remote system can't see the invalid usage anymore, and therefore does not do the validation itself. Users should upgrade to version 4.1.71.Final.",
    "evidence": "osv:DEBIAN-CVE-2021-43797",
    "products": [
      {
        "name": {
          "value": "netty",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:4.1.48-6",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "netty",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:4.1.48-6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "netty",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:4.1.48-6",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2021-43797",
      "aliases": [
        "DEBIAN-CVE-2021-43797"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:4.1.48-6"
                }
              ]
            }
          ],
          "package": {
            "name": "netty",
            "purl": "pkg:deb/debian/netty?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-43797.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:4.1.48-6"
                }
              ]
            }
          ],
          "package": {
            "name": "netty",
            "purl": "pkg:deb/debian/netty?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-43797.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:4.1.48-6"
                }
              ]
            }
          ],
          "package": {
            "name": "netty",
            "purl": "pkg:deb/debian/netty?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-43797.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-09T09:47:23.394352966Z",
      "provider": "osv",
      "upstream": [
        "CVE-2021-43797"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2021-43797"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2021-43797",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 111437,
  "published_at": "2021-12-09T19:15:07.96+00:00"
}