CVE-2024-27416 in Linux
Summary
by MITRE • 05/17/2024
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_event: Fix handling of HCI_EV_IO_CAPA_REQUEST
If we received HCI_EV_IO_CAPA_REQUEST while HCI_OP_READ_REMOTE_EXT_FEATURES is yet to be responded assume the remote does support SSP since otherwise this event shouldn't be generated.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/17/2025
The vulnerability identified as CVE-2024-27416 represents a critical flaw in the Linux kernel's Bluetooth implementation that specifically affects the handling of IO capability requests within the HCI (Host Controller Interface) event processing subsystem. This issue manifests when the kernel receives an HCI_EV_IO_CAPA_REQUEST event while still awaiting a response to a previously issued HCI_OP_READ_REMOTE_EXT_FEATURES command. The improper handling of this temporal race condition creates a potential security risk that could be exploited by malicious actors to manipulate Bluetooth connection establishment processes.
The technical flaw stems from the kernel's Bluetooth subsystem failing to properly account for the timing relationship between different HCI commands and events during the secure connection establishment process. When the HCI_EV_IO_CAPA_REQUEST event arrives before the expected response to HCI_OP_READ_REMOTE_EXT_FEATURES, the kernel incorrectly assumes that the remote device supports Secure Simple Pairing (SSP) capabilities without proper validation. This assumption bypasses normal security checks and could lead to improper authentication state management within the Bluetooth connection framework. The vulnerability resides in the hci_event handling function where the kernel fails to maintain proper state tracking during concurrent Bluetooth command processing operations.
The operational impact of this vulnerability extends beyond simple connection behavior issues and could potentially enable man-in-the-middle attacks or authentication bypass scenarios within Bluetooth networks. An attacker positioned to intercept or manipulate Bluetooth traffic could exploit this timing race condition to force the kernel into an insecure state where it incorrectly assumes SSP support from remote devices. This misconfiguration could weaken the overall security posture of Bluetooth connections, particularly in environments where secure pairing protocols are expected to be enforced. The vulnerability affects systems running Linux kernels that implement the Bluetooth HCI subsystem, potentially impacting a wide range of devices including smartphones, laptops, IoT devices, and embedded systems that rely on Bluetooth connectivity.
Security mitigations for this vulnerability require kernel updates that properly handle the temporal relationship between HCI commands and events, ensuring that IO capability requests are only processed after proper validation of remote device capabilities. System administrators should prioritize applying the latest kernel patches that address this specific race condition in the Bluetooth subsystem. Additional defensive measures include implementing proper Bluetooth security policies, monitoring for unusual connection patterns that might indicate exploitation attempts, and ensuring that Bluetooth services are properly configured with appropriate security levels. Organizations should also consider implementing network segmentation to limit potential attack surfaces and regularly audit Bluetooth connectivity configurations to maintain secure wireless communication environments.
This vulnerability aligns with CWE-367 weakness category related to Time-of-Check to Time-of-Use (TOCTOU) errors, where the system state changes between validation and actual use operations. The issue demonstrates how improper state management in concurrent systems can create security vulnerabilities that may not be immediately obvious during normal operation. From an ATT&CK framework perspective, this vulnerability could be leveraged in initial access or privilege escalation phases of attacks targeting Bluetooth-enabled systems, particularly in environments where Bluetooth is used for device pairing or network access control. The fix implemented in the kernel addresses the core race condition by ensuring proper state validation before processing IO capability requests, thereby preventing unauthorized assumption of secure pairing capabilities.