What’s Vulnerable › Vulnerabilities

CVE-2026-54412: MQTT-C Heap Out-of-Bounds Read and Integer Underflow in mqtt_unpack_publish_response()

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-14 · updated 2026-08-10
• Weakness: CWE-125

Description

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.

Affected products

• LiamBindle MQTT-C: through 1.1.6

References

• https://cwe.mitre.org/data/definitions/125.html
• https://cwe.mitre.org/data/definitions/191.html
• https://github.com/LiamBindle/MQTT-C
• https://github.com/LiamBindle/MQTT-C/blob/v1.1.6/src/mqtt.c#L1334

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