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Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass

Type: advisorySources: OSV

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, a remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of `CONTINUATION` frames. The server's lack of a limit on the number of `CONTINUATION` frames, combined with a bypass of existing size-based mitigations using zero-byte frames, allows an user to cause excessive CPU consumption with minimal bandwidth, rendering the server unresponsive. Versions 4.1.132.Final and 4.2.10.Final fix the issue.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-33871
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 05:39 UTC · Revision 1

Source evidence

Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass

core-osv · Original source

Published 27 Mar 2026, 19:55 UTC

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, a remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of `CONTINUATION` frames. The server's lack of a limit on the number of `CONTINUATION` frames, combined with a bypass of existing size-based mitigations using zero-byte frames, allows an user to cause excessive CPU consumption with minimal bandwidth, rendering the server unresponsive. Versions 4.1.132.Final and 4.2.10.Final fix the issue.

osv:CVE-2026-33871
Complete source record
{
  "id": "c4f0fb2f87d3a62b2556481f02ab71ff7ce235ecb901172a3e6e6af6a5c67285",
  "url": "https://osv.dev/vulnerability/CVE-2026-33871",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass",
    "summary": "Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, a remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of `CONTINUATION` frames. The server's lack of a limit on the number of `CONTINUATION` frames, combined with a bypass of existing size-based mitigations using zero-byte frames, allows an user to cause excessive CPU consumption with minimal bandwidth, rendering the server unresponsive. Versions 4.1.132.Final and 4.2.10.Final fix the issue.",
    "evidence": "osv:CVE-2026-33871",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-33871",
      "aliases": [
        "CVE-2026-33871",
        "GHSA-w9fj-cfpg-grvv"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/netty/netty",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "ec119d487b3a27e4ac118e7e1d97f0c96a85f4a3"
                },
                {
                  "introduced": "09e64d259c99be8b5b2a471a78f11e65eb82598a"
                },
                {
                  "fixed": "4cc98736c3947bc93122e0b64e0bd8fc970c6437"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.1.132"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "4.2.0"
                      },
                      {
                        "fixed": "4.2.10"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "netty-4.1.131.Final",
            "netty-4.2.9.Final",
            "netty-4.1.130.Final",
            "netty-4.2.8.Final",
            "netty-4.1.129.Final",
            "netty-4.1.128.Final",
            "netty-4.2.7.Final",
            "netty-4.2.6.Final",
            "netty-4.1.127.Final",
            "netty-4.2.5.Final",
            "netty-4.1.126.Final",
            "netty-4.1.125.Final",
            "netty-4.2.4.Final",
            "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",
            "netty-4.1.116.Final",
            "netty-4.1.115.Final",
            "netty-4.1.114.Final",
            "netty-4.1.113.Final",
            "netty-4.1.112.Final",
            "netty-4.1.111.Final",
            "netty-4.1.110.Final",
            "netty-4.1.109.Final",
            "netty-4.1.108.Final",
            "netty-4.1.107.Final",
            "netty-4.1.106.Final",
            "netty-4.1.105.Final",
            "netty-4.1.104.Final",
            "netty-4.1.103.Final",
            "netty-4.1.102.Final",
            "netty-4.1.101.Final",
            "netty-4.1.100.Final",
            "netty-4.1.99.Final",
            "netty-4.1.98.Final",
            "netty-4.1.97.Final",
            "netty-4.1.96.Final",
            "netty-4.1.95.Final",
            "netty-4.1.94.Final",
            "netty-4.1.93.Final",
            "netty-4.1.92.Final",
            "netty-4.1.91.Final",
            "netty-4.1.90.Final",
            "netty-4.1.89.Final",
            "netty-4.1.88.Final",
            "netty-4.1.87.Final",
            "netty-4.1.86.Final",
            "netty-4.1.85.Final",
            "netty-4.1.84.Final",
            "netty-4.1.83.Final",
            "netty-4.1.82.Final",
            "netty-4.1.81.Final",
            "netty-4.1.80.Final",
            "netty-4.1.79.Final",
            "netty-4.1.78.Final",
            "netty-4.1.77.Final",
            "netty-4.1.76.Final",
            "netty-4.1.75.Final",
            "netty-4.1.74.Final",
            "netty-4.1.73.Final",
            "netty-4.1.72.Final",
            "netty-4.1.71.Final",
            "netty-4.1.70.Final",
            "netty-4.1.69.Final",
            "netty-4.1.68.Final",
            "netty-4.1.67.Final",
            "netty-4.1.66.Final",
            "netty-4.1.65.Final",
            "netty-4.1.64.Final",
            "netty-4.1.63.Final",
            "netty-4.1.62.Final",
            "netty-4.1.61.Final",
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            "netty-4.1.59.Final",
            "netty-4.1.58.Final",
            "netty-4.1.57.Final",
            "netty-4.1.56.Final",
            "netty-4.1.55.Final",
            "netty-4.1.54.Final",
            "netty-4.1.53.Final",
            "netty-4.1.52.Final",
            "netty-4.1.51.Final",
            "netty-4.1.50.Final",
            "netty-4.1.49.Final",
            "netty-4.1.48.Final",
            "netty-4.1.47.Final",
            "netty-4.1.46.Final",
            "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",
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            "netty-4.1.38.Final",
            "netty-4.1.37.Final",
            "netty-4.1.36.Final",
            "netty-4.1.35.Final",
            "netty-4.1.34.Final",
            "netty-4.1.33.Final",
            "netty-4.1.32.Final",
            "netty-4.1.31.Final",
            "netty-4.1.30.Final",
            "netty-4.1.29.Final",
            "netty-4.1.28.Final",
            "netty-4.1.27.Final",
            "netty-4.1.26.Final",
            "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",
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            "netty-4.1.15.Final",
            "netty-4.1.14.Final",
            "netty-4.1.13.Final",
            "netty-4.1.12.Final",
            "netty-4.1.11.Final",
            "netty-4.1.10.Final",
            "netty-4.1.9.Final",
            "netty-4.1.8.Final",
            "netty-4.1.7.Final",
            "netty-4.1.6.Final",
            "netty-4.1.5.Final",
            "netty-4.1.4.Final",
            "netty-4.1.3.Final",
            "netty-4.1.2.Final",
            "netty-4.1.1.Final",
            "netty-4.1.0.Final",
            "netty-4.1.0.CR7",
            "netty-4.1.0.CR6",
            "netty-4.1.0.CR5",
            "netty-4.1.0.CR4",
            "netty-4.1.0.CR3",
            "netty-4.1.0.CR2",
            "netty-4.1.0.CR1",
            "netty-4.1.0.Beta8",
            "netty-4.1.0.Beta7",
            "netty-4.1.0.Beta6",
            "netty-4.1.0.Beta5",
            "netty-4.1.0.Beta4",
            "netty-4.1.0.Beta3",
            "netty-4.1.0.Beta2",
            "netty-4.1.0.Beta1",
            "netty-4.0.15.Final",
            "netty-4.0.14.Final",
            "netty-4.0.14.Beta1",
            "netty-4.0.13.Final",
            "netty-4.0.12.Final",
            "netty-4.0.11.Final",
            "netty-4.0.10.Final",
            "netty-4.0.8.Final",
            "netty-4.0.7.Final",
            "netty-4.0.6.Final",
            "netty-4.0.5.Final",
            "netty-4.0.4.Final",
            "netty-4.0.3.Final",
            "netty-4.0.2.Final",
            "netty-4.0.1.Final",
            "netty-4.0.0.Final",
            "netty-4.0.0.CR9",
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            "netty-4.0.0.CR5",
            "netty-4.0.0.CR4",
            "netty-4.0.0.CR3",
            "netty-4.0.0.CR2",
            "netty-4.0.0.CR1",
            "netty-4.0.0.Beta3",
            "netty-4.0.0.Beta2",
            "netty-4.0.0.Beta1",
            "netty-4.0.0.Alpha8",
            "netty-4.0.0.Alpha7",
            "netty-4.0.0.Alpha6",
            "netty-4.0.0.Alpha5",
            "netty-4.0.0.Alpha4",
            "netty-4.0.0.Alpha3",
            "netty-4.0.0.Alpha2",
            "netty-4.0.0.Alpha1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33871.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.446813325Z",
      "provider": "osv",
      "references": [
        "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33871.json",
        "https://access.redhat.com/errata/RHSA-2026:10175",
        "https://access.redhat.com/errata/RHSA-2026:10184",
        "https://access.redhat.com/errata/RHSA-2026:13571",
        "https://access.redhat.com/errata/RHSA-2026:14272",
        "https://access.redhat.com/errata/RHSA-2026:14276",
        "https://access.redhat.com/errata/RHSA-2026:17668",
        "https://access.redhat.com/errata/RHSA-2026:17789",
        "https://access.redhat.com/errata/RHSA-2026:18054",
        "https://access.redhat.com/errata/RHSA-2026:18055",
        "https://access.redhat.com/errata/RHSA-2026:18059",
        "https://access.redhat.com/errata/RHSA-2026:22619",
        "https://access.redhat.com/errata/RHSA-2026:34608",
        "https://access.redhat.com/errata/RHSA-2026:65126",
        "https://access.redhat.com/errata/RHSA-2026:7109",
        "https://access.redhat.com/errata/RHSA-2026:7380",
        "https://access.redhat.com/errata/RHSA-2026:8159",
        "https://access.redhat.com/errata/RHSA-2026:8509",
        "https://access.redhat.com/security/cve/CVE-2026-33871",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33871.json",
        "https://github.com/netty/netty/security/advisories/GHSA-w9fj-cfpg-grvv",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-33871",
        "https://bugzilla.redhat.com/show_bug.cgi?id=2452456"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-770"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33871.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-33871",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492785,
  "published_at": "2026-03-27T19:55:23.135+00:00"
}