CVE-2016-10523 in MQTT
Summary
by MITRE
MQTT before 3.4.6 and 4.0.x before 4.0.5 allows specifically crafted MQTT packets to crash the application, making a DoS attack feasible with very little bandwidth.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/17/2023
The vulnerability identified as CVE-2016-10523 represents a critical denial of service weakness in MQTT (Message Queuing Telemetry Transport) protocol implementations prior to specific version releases. This vulnerability affects MQTT versions 3.4.5 and earlier, as well as 4.0.x versions before 4.0.5, exposing systems that rely on MQTT for message brokering to potential disruption attacks. The flaw stems from inadequate input validation mechanisms within the MQTT parser, which fails to properly handle malformed or specially crafted packets that could trigger unexpected application behavior. The vulnerability specifically targets the protocol's packet processing logic where the application does not adequately sanitize incoming data structures, leading to memory corruption or stack overflow conditions when processing maliciously constructed MQTT frames.
The technical implementation of this vulnerability exploits the lack of proper bounds checking and input validation in the MQTT protocol handler. Attackers can construct specific MQTT packets containing malformed data fields, oversized payloads, or invalid control characters that cause the receiving application to crash or terminate unexpectedly. These crafted packets require minimal network bandwidth to execute, making them particularly effective for resource-constrained attack environments where network capacity is limited. The vulnerability operates at the application layer of the network stack, affecting MQTT brokers and clients that process incoming messages without sufficient defensive mechanisms. The flaw is categorized under CWE-129 Input Validation and CWE-20 Improper Input Validation, representing a classic example of insufficient data sanitization that leads to application instability.
The operational impact of CVE-2016-10523 extends beyond simple service disruption to potentially compromise entire IoT ecosystems and industrial control systems that depend on MQTT for communication. When exploited, the vulnerability can cause cascading failures in connected systems where MQTT brokers serve as central message routing points, leading to widespread service outages across dependent applications. Organizations utilizing MQTT for critical infrastructure monitoring, smart grid communications, or industrial automation are particularly vulnerable to this attack vector, as the low bandwidth requirement makes it feasible to launch sustained denial of service attacks. The vulnerability also enables attackers to potentially gain insights into system configurations through crash analysis, providing information that could aid in subsequent exploitation attempts. According to ATT&CK framework, this vulnerability maps to T1499.004 Network Denial of Service and T1071.004 Application Layer Protocol, highlighting its potential for both direct service disruption and protocol manipulation.
Mitigation strategies for CVE-2016-10523 require immediate implementation of software updates to MQTT versions 3.4.6 or 4.0.5, which contain patches addressing the input validation deficiencies. Organizations should also implement network-level filtering to restrict incoming MQTT traffic and deploy intrusion detection systems that can identify and block suspicious packet patterns. Additional defensive measures include implementing rate limiting mechanisms to prevent excessive packet processing, deploying application firewalls with protocol-aware inspection capabilities, and establishing monitoring procedures to detect unusual application crash patterns. The vulnerability underscores the importance of secure coding practices in protocol implementations and the necessity of comprehensive input validation across all network-facing applications. Security teams should conduct thorough vulnerability assessments of their MQTT deployments and implement network segmentation to limit the potential impact of successful exploitation attempts. Regular security updates and patch management processes become critical for maintaining the integrity of MQTT-based systems against similar vulnerabilities that may emerge in the future.