CVE-2017-7655 in Mosquitto
Summary
by MITRE
In Eclipse Mosquitto version from 1.0 to 1.4.15, a Null Dereference vulnerability was found in the Mosquitto library which could lead to crashes for those applications using the library.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 08/08/2023
The Eclipse Mosquitto project represents a widely deployed open source message broker implementation that adheres to the mqtt protocol standard and serves as a foundational component in numerous internet of things deployments and messaging infrastructure. This particular vulnerability exists within the library's handling of client connections and message processing mechanisms, specifically affecting versions ranging from 1.0 through 1.4.15. The flaw manifests as a null pointer dereference condition that occurs when the library attempts to process certain malformed or unexpected input sequences from connected clients. This vulnerability falls under the common weakness enumeration CWE-476 which categorizes null pointer dereference conditions as a critical class of software defects that can lead to application instability and potential system compromise.
The technical execution of this vulnerability occurs when the Mosquitto library receives a malformed message or connection sequence that triggers a code path where a pointer variable intended to reference a valid memory location remains uninitialized or explicitly set to null. When the application subsequently attempts to dereference this null pointer during message processing or connection handling operations, the system experiences an immediate crash or segmentation fault. This behavior represents a denial of service condition that can be exploited by remote attackers who send specifically crafted messages to vulnerable instances. The vulnerability is particularly concerning because it affects the core library functionality and can be triggered through normal client communication patterns without requiring special privileges or authentication.
The operational impact of this vulnerability extends beyond simple service disruption as it can affect large scale deployments where Mosquitto serves as a critical messaging backbone for industrial control systems, smart city infrastructure, and IoT networks. When exploited, the null dereference causes the broker process to terminate unexpectedly, requiring manual intervention to restart services and potentially leading to message loss or communication gaps in connected systems. The vulnerability's exploitation is relatively straightforward since it only requires sending malformed data to a running broker instance, making it particularly dangerous in environments where automated systems rely on continuous messaging availability. From an attack perspective, this vulnerability aligns with ATT&CK technique T1499.004 which describes denial of service attacks targeting network infrastructure components.
Organizations utilizing affected versions of Mosquitto should implement immediate mitigation strategies including applying the patched versions released by the Eclipse Foundation, which address the null pointer dereference by adding proper input validation and null checks before pointer dereference operations. Network segmentation and access controls should be implemented to limit exposure of vulnerable instances to untrusted networks, while monitoring systems should be deployed to detect unusual connection patterns or crash events that may indicate exploitation attempts. The fix typically involves adding defensive programming practices such as null pointer validation before memory access operations, which aligns with secure coding guidelines established by both CWE and industry best practices for preventing memory safety issues in C/C++ based applications. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of the vulnerable software within organizational networks and ensure comprehensive remediation across all deployment environments.