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FKIE_CVE-2026-93575

Vulnerability from fkie_nvd - Published: 2026-09-18 11:17 - Updated: 2026-09-18 11:17
Severity
Summary
### Summary Netty's fix for CVE-2026-44248 is incomplete. The decoder checks if the MQTT packet's `Remaining Length` exceeds `maxBytesInMessage`, but fails to validate the `Properties Length` against the `Remaining Length`. An attacker can bypass the size limit by sending a small `Remaining Length` but an enormous `Properties Length`. This forces Netty to buffer and parse millions of properties, allowing an unauthenticated remote attacker to trigger excessive memory and CPU consumption, leading to OutOfMemoryError. ### Details In `io.netty.handler.codec.mqtt.MqttDecoder`, the `decodeProperties()` helper method reads `totalPropertiesLength` and attempts to parse that many bytes. If the buffer lacks the full length, a `Signal` is thrown. The `catch` block inside `decode()` only enforces `maxBytesInMessage` against `bytesRemainingBeforeVariableHeader` (the packet's `Remaining Length`). By sending a `CONNECT` packet with a small `Remaining Length` but a huge `Properties Length`, the size check passes. `ReplayingDecoder` then buffers data from the network until the huge `Properties Length` is reached, parsing millions of `UserProperty` objects and exhausting CPU and memory. #
References
secalert@redhat.comhttps://access.redhat.com/security/cve/CVE-2026-93575
secalert@redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2536967
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:amq_broker:7"
          ],
          "defaultStatus": "affected",
          "packageName": "netty-codec-mqtt",
          "product": "Red Hat AMQ Broker 7",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:camel_spring_boot:4"
          ],
          "defaultStatus": "affected",
          "packageName": "netty-codec-mqtt",
          "product": "Red Hat build of Apache Camel for Spring Boot 4",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:jboss_fuse:7"
          ],
          "defaultStatus": "affected",
          "packageName": "netty-codec-mqtt",
          "product": "Red Hat Fuse 7",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ],
          "defaultStatus": "affected",
          "packageName": "jboss-eap-7/eap74-els-openjdk11-openshift-rhel8",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ],
          "defaultStatus": "affected",
          "packageName": "jboss-eap-7/eap74-els-openjdk17-openshift-rhel8",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ],
          "defaultStatus": "affected",
          "packageName": "jboss-eap-7/eap74-els-openjdk8-openshift-rhel8",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ],
          "defaultStatus": "affected",
          "packageName": "netty-codec-mqtt",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:red_hat_single_sign_on:7"
          ],
          "defaultStatus": "affected",
          "packageName": "netty-codec-mqtt",
          "product": "Red Hat Single Sign-On 7",
          "vendor": "Red Hat"
        }
      ],
      "source": "secalert@redhat.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "### Summary\r\nNetty\u0027s fix for CVE-2026-44248 is incomplete. The decoder checks if the MQTT packet\u0027s `Remaining Length` exceeds `maxBytesInMessage`, but fails to validate the `Properties Length` against the `Remaining Length`. An attacker can bypass the size limit by sending a small `Remaining Length` but an enormous `Properties Length`. This forces Netty to buffer and parse millions of properties, allowing an unauthenticated remote attacker to trigger excessive memory and CPU consumption, leading to OutOfMemoryError.\r\n\r\n### Details\r\nIn `io.netty.handler.codec.mqtt.MqttDecoder`, the `decodeProperties()` helper method reads `totalPropertiesLength` and attempts to parse that many bytes. If the buffer lacks the full length, a `Signal` is thrown. The `catch` block inside `decode()` only enforces `maxBytesInMessage` against `bytesRemainingBeforeVariableHeader` (the packet\u0027s `Remaining Length`).\r\n\r\nBy sending a `CONNECT` packet with a small `Remaining Length` but a huge `Properties Length`, the size check passes. `ReplayingDecoder` then buffers data from the network until the huge `Properties Length` is reached, parsing millions of `UserProperty` objects and exhausting CPU and memory.\r\n\r\n#"
    }
  ],
  "id": "CVE-2026-93575",
  "lastModified": "2026-09-18T11:17:22.033",
  "metrics": {},
  "published": "2026-09-18T11:17:22.033",
  "references": [
    {
      "source": "secalert@redhat.com",
      "url": "https://access.redhat.com/security/cve/CVE-2026-93575"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2536967"
    }
  ],
  "sourceIdentifier": "secalert@redhat.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1035"
        }
      ],
      "source": "secalert@redhat.com",
      "type": "Primary"
    }
  ]
}



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