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        "cveId": "CVE-2026-5857",
        "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "state": "PUBLISHED",
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        "dateReserved": "2026-04-08T19:29:27.852Z",
        "datePublished": "2026-08-06T18:52:40.005Z",
        "dateUpdated": "2026-08-14T16:50:27.644Z"
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            "title": "Contiki-NG MQTT Client Out-of-Bounds Write in PUBLISH Topic Parser via Persistent State Between TCP Segments",
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                {
                    "lang": "en",
                    "value": "Contiki-NG's MQTT client parse_publish_vhdr() in os/net/app-layer/mqtt/mqtt.c sets topic_len_received=1 before checking topic_len against the 64-byte limit, so an over-length topic returns early but leaves the flag set. On the next TCP segment, tcp_input() re-invokes the parser with topic_received==0, and the persisted topic_len_received==1 skips the length-reading block containing the guard, falling through directly to a memcpy() that uses the unvalidated 16-bit topic_len as the copy length. The 65-byte topic[] destination overruns into adjacent struct fields including the payload_chunk pointer, which subsequent MQTT code dereferences, giving a compromised or attacker-controlled broker an arbitrary-pointer-write primitive. Contiki-NG's MQTT implementation has no TLS support so the connection is plaintext. Impact ranges from information disclosure and denial of service to remote code execution on embedded targets without memory protection."
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                            "cweId": "CWE-787",
                            "description": "Out-of-bounds Write",
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                    "value": "Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc.",
                    "type": "reporter"
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