GHSA-563Q-J3CM-6JXM

Vulnerability from github – Published: 2026-06-15 20:46 – Updated: 2026-06-15 20:46
VLAI
Summary
Netty susceptible to HTTP/2 Reset Attack with different on-the-wire signature
Details

Summary

Netty HTTP/2 max header size handling produces attack similar to HTTP/2 Rapid Reset.

Details

There is a setting in the http2 specification called SETTINGS_MAX_HEADER_LIST_SIZE. According to the RFC: “This advisory setting informs a peer of the maximum field section size that the sender is prepared to accept, in units of octets.”

When a client sends that setting to Netty, it appears that Netty will behave as follows:

  • Read the request
  • Proxy the request to the origin
  • Attempt to produce a response
  • Create an exception while writing the headers for the response

Functionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature.

Remediation

When speaking with clients, Netty should potentially treat this as “advisory” and ignore it. It would be best to ignore the SETTINGS_MAX_HEADER_LIST_SIZE setting from clients (or ignore it when sending to clients). According to the spec, a server does not need to honor this advisory setting, and it appears that other http/2 implementations ignore it when acting as a server.

Impact

This is a DDoS attack similar to the HTTP/2 Rapid Reset Attack.

Credit

Jonathan Looney (Engineering, Netflix)

Contact

Ashley Tolbert (Security, Netflix) - artolbert@netflix.com

Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.2.14.Final"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "io.netty:netty-codec-http2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.2.0.Final"
            },
            {
              "fixed": "4.2.15.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.1.134.Final"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "io.netty:netty-codec-http2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.135.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-50560"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-15T20:46:56Z",
    "nvd_published_at": "2026-06-12T16:16:32Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nNetty HTTP/2 max header size handling produces attack similar to HTTP/2 Rapid Reset.\n\n### Details\n\nThere is a setting in the http2 specification called `SETTINGS_MAX_HEADER_LIST_SIZE`. According to[ the RFC](https://www.rfc-editor.org/rfc/rfc9113.html#name-defined-settings): \u201cThis advisory setting informs a peer of the maximum field section size that the sender is prepared to accept, in units of octets.\u201d\n\nWhen a client sends that setting to Netty, it appears that Netty will behave as follows:\n\n- Read the request\n- Proxy the request to the origin\n- Attempt to produce a response\n- Create an exception while writing the headers for the response\n\nFunctionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature.\n\n## Remediation\n\nWhen speaking with clients, Netty should potentially treat this as \u201cadvisory\u201d and ignore it.  It would be best to ignore the SETTINGS_MAX_HEADER_LIST_SIZE setting from clients (or ignore it when sending to clients). According to the spec, a server does not need to honor this advisory setting, and it appears that other http/2 implementations ignore it when acting as a server.\n\n### Impact\n\nThis is a DDoS attack similar to the HTTP/2 Rapid Reset Attack.\n\n## Credit\nJonathan Looney (Engineering, Netflix)\n\n## Contact\nAshley Tolbert (Security, Netflix) - artolbert@netflix.com",
  "id": "GHSA-563q-j3cm-6jxm",
  "modified": "2026-06-15T20:46:56Z",
  "published": "2026-06-15T20:46:56Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty/security/advisories/GHSA-563q-j3cm-6jxm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-50560"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/netty/netty"
    },
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty/releases/tag/netty-4.1.135.Final"
    },
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty/releases/tag/netty-4.2.15.Final"
    },
    {
      "type": "WEB",
      "url": "https://www.rfc-editor.org/rfc/rfc9113.html#name-defined-settings"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Netty susceptible to HTTP/2 Reset Attack with different on-the-wire signature"
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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