{"document":{"category":"csaf_vex","csaf_version":"2.0","title":"CVE-2026-54412: LiamBindle MQTT-C through version 1","publisher":{"category":"vendor","name":"HarborGuard Database","namespace":"https://database.harborguard.co"},"tracking":{"id":"CVE-2026-54412","status":"final","version":"1","initial_release_date":"2026-06-14T17:26:36.740Z","current_release_date":"2026-06-14T17:27:35.016Z","revision_history":[{"date":"2026-06-14T17:26:36.740Z","number":"1","summary":"Initial machine-readable export from HarborGuard."}]},"distribution":{"tlp":{"label":"WHITE"},"text":"Public CVE data; freely redistributable."},"notes":[{"category":"description","text":"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.","title":"CVE description"}],"references":[{"category":"self","summary":"CVE-2026-54412 on HarborGuard Database","url":"https://database.harborguard.co/cve/CVE-2026-54412"},{"category":"external","summary":"CVE Record","url":"https://www.cve.org/CVERecord?id=CVE-2026-54412"},{"category":"external","summary":"LiamBindle/MQTT-C - upstream repository (unmaintained since 2022-10-27)","url":"https://github.com/LiamBindle/MQTT-C"},{"category":"external","summary":"Vulnerable mqtt_unpack_publish_response() in src/mqtt.c (v1.1.6)","url":"https://github.com/LiamBindle/MQTT-C/blob/v1.1.6/src/mqtt.c#L1334"},{"category":"external","summary":"CWE-125: Out-of-bounds Read","url":"https://cwe.mitre.org/data/definitions/125.html"},{"category":"external","summary":"CWE-191: Integer Underflow (Wrap or Wraparound)","url":"https://cwe.mitre.org/data/definitions/191.html"}]},"product_tree":{"branches":[{"category":"vendor","name":"LiamBindle","branches":[{"category":"product_name","name":"MQTT-C","branches":[{"category":"product_version_range","name":"<=1.1.6","product":{"name":"LiamBindle MQTT-C <=1.1.6","product_id":"CSAFPID-1","product_identification_helper":{"cpe":"cpe:2.3:a:liambindle:mqtt-c:*:*:*:*:*:*:*:*"}}}]}]}]},"vulnerabilities":[{"cve":"CVE-2026-54412","title":"LiamBindle MQTT-C through version 1","notes":[{"category":"description","text":"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.","title":"CVE description"}],"product_status":{"known_affected":["CSAFPID-1"]},"scores":[{"cvss_v4":{"version":"4.0","vectorString":"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","baseScore":7.8,"baseSeverity":"HIGH"},"products":["CSAFPID-1"]}],"remediations":[{"category":"none_available","details":"No fixed version is published yet. Monitor the upstream advisory.","product_ids":["CSAFPID-1"]}]}]}