GHSA-JFG9-48MV-9QGX

Vulnerability from github – Published: 2026-05-07 05:14 – Updated: 2026-05-14 20:41
VLAI
Summary
Netty MQTT: Resource exhaustion in MqttDecoder
Details

Impact

The MQTT 5 header Properties section is parsed and buffered before any message size limit is applied.

Specifically, in MqttDecoder, the decodeVariableHeader() method is called before the bytesRemainingBeforeVariableHeader > maxBytesInMessage check. The decodeVariableHeader() can call other methods which will call decodeProperties(). Effectively, Netty does not apply any limits to the size of the properties being decoded.

Additionally, because MqttDecoder extends ReplayingDecoder, Netty will repeatedly re-parse the enormous Properties sections and buffer the bytes in memory, until the entire thing parses to completion.

This can cause high resource usage in both CPU and memory.

Resources

ANT-2026-09608 https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901027

Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Show details on source website
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.2.12.Final"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "io.netty:netty-codec-mqtt"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.2.0.Alpha1"
            },
            {
              "fixed": "4.2.13.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.1.132.Final"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "io.netty:netty-codec-mqtt"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.133.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44248"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-07T05:14:14Z",
    "nvd_published_at": "2026-05-13T19:17:27Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nThe MQTT 5 header Properties section is parsed and buffered _before_ any message size limit is applied.\n\nSpecifically, in `MqttDecoder`, the `decodeVariableHeader()` method is called before the `bytesRemainingBeforeVariableHeader \u003e maxBytesInMessage` check. The `decodeVariableHeader()` can call other methods which will call `decodeProperties()`. Effectively, Netty does not apply any limits to the size of the properties being decoded.\n\nAdditionally, because `MqttDecoder` extends `ReplayingDecoder`, Netty will repeatedly re-parse the enormous Properties sections and buffer the bytes in memory, until the entire thing parses to completion.\n\nThis can cause high resource usage in both CPU and memory.\n\n### Resources\n`ANT-2026-09608`\nhttps://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901027",
  "id": "GHSA-jfg9-48mv-9qgx",
  "modified": "2026-05-14T20:41:33Z",
  "published": "2026-05-07T05:14:14Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty/security/advisories/GHSA-jfg9-48mv-9qgx"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44248"
    },
    {
      "type": "WEB",
      "url": "https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901027"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/netty/netty"
    }
  ],
  "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"
    }
  ],
  "summary": "Netty MQTT: Resource exhaustion in MqttDecoder"
}



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