CVE-2025-44557 in PSoC4
Summary
by MITRE • 06/27/2025
A state machine transition flaw in the Bluetooth Low Energy (BLE) stack of Cypress PSoC4 v3.66 allows attackers to bypass the pairing process and authentication via a crafted pairing_failed packet.
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Analysis
by VulDB Data Team • 06/28/2025
The vulnerability identified as CVE-2025-44557 represents a critical state machine transition flaw within the Bluetooth Low Energy stack implementation of Cypress PSoC4 microcontrollers running firmware version 3.66. This issue resides in the core pairing and authentication mechanisms that govern how BLE devices establish secure connections. The flaw specifically manifests when the system processes a crafted pairing_failed packet, which should normally indicate a failed authentication attempt but instead triggers an unintended state transition that allows attackers to circumvent the complete pairing sequence. This vulnerability directly impacts the fundamental security model of BLE communications and represents a significant deviation from expected protocol behavior.
The technical root cause of this vulnerability stems from insufficient validation and state management within the BLE stack's pairing state machine. When a pairing_failed packet is received, the system should properly terminate the pairing attempt and return to a neutral state. However, the flawed implementation fails to properly validate the packet's authenticity and sequence, allowing malicious actors to manipulate the state transition logic. This flaw can be categorized under CWE-362, which addresses race conditions in concurrent systems, and more specifically aligns with CWE-367, which deals with time-of-check to time-of-use (TOCTOU) vulnerabilities. The vulnerability enables attackers to exploit the timing and sequence dependencies within the pairing process, effectively creating a path for unauthorized device access without proper authentication.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential full system compromise and data exfiltration capabilities. An attacker positioned within Bluetooth range can exploit this flaw to establish unauthorized connections with BLE devices, potentially gaining access to sensitive data, control functions, or serving as a foothold for further attacks within IoT ecosystems. This vulnerability particularly affects embedded systems and IoT devices that rely on PSoC4 microcontrollers for wireless communication, including smart home devices, industrial sensors, and medical equipment. The attack vector requires only proximity and the ability to intercept or inject Bluetooth packets, making it particularly dangerous in environments where physical access is difficult to control. According to ATT&CK framework, this vulnerability maps to T1566.001 (Phishing via Social Engineering) and T1071.001 (Application Layer Protocol: Web Protocols) through the potential for initial access and lateral movement within connected networks.
Mitigation strategies for CVE-2025-44557 must address both immediate defensive measures and long-term architectural improvements. Organizations should prioritize firmware updates from Cypress to address the specific state machine implementation flaw, while implementing network segmentation and monitoring to detect anomalous pairing attempts. Additional protective measures include deploying Bluetooth packet filtering mechanisms, enabling secure pairing protocols such as LE Secure Connections, and implementing continuous monitoring for unauthorized pairing sequences. The vulnerability also highlights the importance of secure state machine design principles and emphasizes the need for comprehensive testing of all possible state transitions in embedded systems. Security teams should conduct thorough assessments of all BLE-enabled devices within their infrastructure, particularly focusing on those using PSoC4 microcontrollers, and implement device authentication mechanisms that do not rely solely on the pairing process for security guarantees.