CVE-2024-10525 in Mosquitto
Summary
by MITRE • 10/30/2024
In Eclipse Mosquitto, from version 1.3.2 through 2.0.18, if a malicious broker sends a crafted SUBACK packet with no reason codes, a client using libmosquitto may make out of bounds memory access when acting in its on_subscribe callback. This affects the mosquitto_sub and mosquitto_rr clients.
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Analysis
by VulDB Data Team • 02/20/2025
The vulnerability CVE-2024-10525 affects Eclipse Mosquitto versions 1.3.2 through 2.0.18 and represents a critical memory safety issue within the libmosquitto library implementation. This flaw manifests when a malicious broker sends a specially crafted SUBACK packet that lacks reason codes, causing client applications to experience out-of-bounds memory access during callback execution. The vulnerability specifically impacts the on_subscribe callback mechanism, which is a fundamental component of MQTT client-server communication protocols. The affected mosquitto_sub and mosquitto_rr client applications are particularly susceptible because they rely on proper packet parsing and callback handling to maintain secure communication channels.
The technical root cause of this vulnerability stems from insufficient input validation within the SUBACK packet processing logic. When the client receives a SUBACK packet without reason codes, the libmosquitto library fails to properly validate the packet structure before attempting to access memory locations that correspond to these missing elements. This memory access violation occurs during the on_subscribe callback execution, where the client attempts to process subscription acknowledgment data that does not conform to expected packet formatting standards. The absence of proper bounds checking and validation creates a pathway for attackers to potentially exploit memory corruption vulnerabilities that could lead to arbitrary code execution or service disruption. This flaw aligns with CWE-129, which addresses insufficient validation of length of inputs, and CWE-787, concerning out-of-bounds write operations.
The operational impact of CVE-2024-10525 extends beyond simple memory corruption, as it can compromise the integrity and availability of MQTT-based communication systems. Client applications that process subscription acknowledgments from potentially malicious brokers may experience crashes, data corruption, or unpredictable behavior when encountering malformed SUBACK packets. The vulnerability affects both mosquitto_sub and mosquitto_rr clients, which are commonly used for subscription management and request-response communication patterns in IoT and messaging infrastructure. Attackers could leverage this weakness to perform denial-of-service attacks against MQTT clients or potentially escalate privileges if the affected applications run with elevated permissions. According to ATT&CK framework, this vulnerability maps to T1499.004, which covers network denial of service, and T1595.001, covering network sniffing through malicious packet injection.
Mitigation strategies for CVE-2024-10525 require immediate attention from system administrators and developers using affected Mosquitto versions. The primary recommendation involves upgrading to Eclipse Mosquitto version 2.0.19 or later, where the vulnerability has been patched through enhanced input validation and proper bounds checking in SUBACK packet processing. Organizations should also implement network segmentation and broker authentication mechanisms to reduce the attack surface and prevent unauthorized broker access. Additionally, developers should review their callback implementations to ensure proper error handling and input validation before processing subscription acknowledgment data. Network monitoring should be enhanced to detect anomalous SUBACK packet patterns that may indicate exploitation attempts. Security teams should also consider implementing intrusion detection systems that can identify and alert on malformed MQTT packets that could be indicators of this specific vulnerability.