Mongoose parse_mqtt() Function Heap-Based Buffer Overflow Vulnerability [CVE-2019-12951]

CVE Number – CVE-2019-12951

A vulnerability in Cesanta Mongoose could allow an unauthenticated, remote attacker to execute arbitrary code or cause a denial of service (DoS) condition on a targeted system.The vulnerability is due to a heap-based buffer overflow condition that exists in the parse_mqtt()function, as defined in the mg_mqtt.c source code file of the affected software. An attacker could exploit this vulnerability by submitting crafted requests to the targeted system. A successful exploit could allow the attacker to execute arbitrary code or cause a DoS condition on a targeted system.The vendor has confirmed the vulnerability and software updates are available.


  • To exploit this vulnerability, the attacker must send a request that submits malicious input to the targeted host system. This access requirement could reduce the likelihood of a successful exploit.


  • Administrators are advised to apply the appropriate updates.Administrators are advised to allow only trusted users to have network access.Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.Administrators can help protect affected systems from external attacks by using a solid firewall strategy.Administrators are advised to monitor affected systems.

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Fixed Software

Jason Davies

UK based technology professional, with an interest in computer security and telecoms.

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