netty — security advisory

{
  "id": "0924faebe21c3af80e52b921c31e816cec6c4c4ebb63e988b5dc8231cc927b9c",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-21295",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2021-21295",
    "summary": "Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty (io.netty:netty-codec-http2) before version 4.1.60.Final there is a vulnerability that enables request smuggling. If a Content-Length header is present in the original HTTP/2 request, the field is not validated by `Http2MultiplexHandler` as it is propagated up. This is fine as long as the request is not proxied through as HTTP/1.1. If the request comes in as an HTTP/2 stream, gets converted into the HTTP/1.1 domain objects (`HttpRequest`, `HttpContent`, etc.) via `Http2StreamFrameToHttpObjectCodec `and then sent up to the child channel's pipeline and proxied through a remote peer as HTTP/1.1 this may result in request smuggling. In a proxy case, users may assume the content-length is validated somehow, which is not the case. If the request is forwarded to a backend channel that is a HTTP/1.1 connection, the Content-Length now has meaning and needs to be checked. An attacker can smuggle requests inside the body as it gets downgraded from HTTP/2 to HTTP/1.1. For an example attack refer to the linked GitHub Advisory. Users are only affected if all of this is true: `HTTP2MultiplexCodec` or `Http2FrameCodec` is used, `Http2StreamFrameToHttpObjectCodec` is used to convert to HTTP/1.1 objects, and these HTTP/1.1 objects are forwarded to another remote peer. This has been patched in 4.1.60.Final As a workaround, t",
    "evidence": "osv:DEBIAN-CVE-2021-21295",
    "products": [
      {
        "name": {
          "value": "netty",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:4.1.48-3",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "netty",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:4.1.48-3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "netty",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:4.1.48-3",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2021-21295",
      "aliases": [
        "DEBIAN-CVE-2021-21295"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:4.1.48-3"
                }
              ]
            }
          ],
          "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-2021-21295.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:4.1.48-3"
                }
              ]
            }
          ],
          "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-2021-21295.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:4.1.48-3"
                }
              ]
            }
          ],
          "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-2021-21295.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-09T09:47:29.841238368Z",
      "provider": "osv",
      "upstream": [
        "CVE-2021-21295"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2021-21295"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2021-21295",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 111575,
  "published_at": "2021-03-09T19:15:12.657+00:00"
}