{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "last_affected": "1.1.6"
              },
              {
                "fixed": "1.1.6"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "DESCRIPTION"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "f69ce1e7fd54f3b1834c9c9137ce0ec5d703cb4d"
            }
          ],
          "repo": "https://github.com/liambindle/mqtt-c",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "TuranSec",
    "cwe_ids": [
      "CWE-125",
      "CWE-191"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54412.json"
  },
  "details": "LiamBindle MQTT-C through version 1.1.6 contains a heap-based out-of-bounds read and integer underflow in the mqtt_unpack_publish_response() function in src/mqtt.c that allows a remote unauthenticated attacker controlling an MQTT broker - or able to inject MQTT traffic into an unencrypted session - to crash a subscribed MQTT-C client and potentially disclose adjacent heap memory by sending a single crafted PUBLISH packet. The function validates only that the fixed-header remaining_length is at least 4, then reads the 16-bit topic_name_size field from the broker-controlled packet and advances the parse pointer by that value without verifying that topic_name_size plus the surrounding overhead fits within remaining_length; it subsequently computes application_message_size as remaining_length - topic_name_size - 2 (QoS 0) or - 4 (QoS greater than 0) in unsigned arithmetic, producing an integer underflow that is then passed to memmove(). A PUBLISH packet with topic_name_size = 0xFFFF and remaining_length = 7 advances the parse pointer 65535 bytes past the receive buffer (out-of-bounds read) and causes an application_message_size near 2^32, crashing the process when the resulting memmove() is executed.",
  "id": "CVE-2026-54412",
  "modified": "2026-07-08T05:38:25.296769653Z",
  "published": "2026-06-14T17:26:36.740Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/LiamBindle/MQTT-C/blob/v1.1.6/src/mqtt.c#L1334"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54412.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54412"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/LiamBindle/MQTT-C"
    },
    {
      "type": "ARTICLE",
      "url": "https://cwe.mitre.org/data/definitions/125.html"
    },
    {
      "type": "ARTICLE",
      "url": "https://cwe.mitre.org/data/definitions/191.html"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/AU:Y/V:D",
      "type": "CVSS_V4"
    }
  ]
}