{
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          "vendor": "netty",
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              "status": "affected",
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          "lang": "en",
          "value": "Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.137.Final and 4.2.17.Final, MqttEncoder does not validate client identifiers, will topics, usernames, and PUBLISH topic names before encoding, allowing prohibited null bytes in MQTT UTF-8 string fields and potentially causing routing, access-control, or identity mismatches in downstream brokers. The vulnerability is exploitable when an application uses Netty\u0027s MQTT encoder to construct messages from user-controlled input. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 3.5,
            "baseSeverity": "LOW",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-20",
              "description": "CWE-20: Improper Input Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-626",
              "description": "CWE-626: Null Byte Interaction Error (Poison Null Byte)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-24T19:53:12.737Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/netty/netty/security/advisories/GHSA-43fm-7cxg-hf3j",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/netty/netty/security/advisories/GHSA-43fm-7cxg-hf3j"
        },
        {
          "name": "https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7"
        },
        {
          "name": "https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961"
        }
      ],
      "source": {
        "advisory": "GHSA-43fm-7cxg-hf3j",
        "discovery": "UNKNOWN"
      },
      "title": "Netty: MQTT Topic Name and Client ID Validation Bypass"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-76816",
    "datePublished": "2026-08-24T19:53:12.737Z",
    "dateReserved": "2026-08-19T19:52:28.213Z",
    "dateUpdated": "2026-08-24T19:53:12.737Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-76816\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-24T20:17:19.477\",\"lastModified\":\"2026-08-24T20:17:19.477\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.137.Final and 4.2.17.Final, MqttEncoder does not validate client identifiers, will topics, usernames, and PUBLISH topic names before encoding, allowing prohibited null bytes in MQTT UTF-8 string fields and potentially causing routing, access-control, or identity mismatches in downstream brokers. The vulnerability is exploitable when an application uses Netty\u0027s MQTT encoder to construct messages from user-controlled input. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"netty\",\"product\":\"netty\",\"versions\":[{\"version\":\"\u003e= 4.2.0.Final, \u003c 4.1.137.Final\",\"status\":\"affected\"},{\"version\":\"\u003c 4.1.137.Final\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N\",\"baseScore\":3.5,\"baseSeverity\":\"LOW\",\"attackVector\":\"ADJACENT_NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.1,\"impactScore\":1.4}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-20\"},{\"lang\":\"en\",\"value\":\"CWE-626\"}]}],\"references\":[{\"url\":\"https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/netty/netty/security/advisories/GHSA-43fm-7cxg-hf3j\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}