CVE-2026-74301 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: btmtk: fix URB leak in alloc_mtk_intr_urb error path
When btmtk_isopkt_pad() fails, the previously allocated URB is not freed, leaking the urb structure. Add usb_free_urb() before returning the error.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability resides within the Linux kernel's Bluetooth subsystem, specifically affecting the MediaTek Bluetooth driver implementation known as btmtk. The issue manifests as a memory leak during error handling conditions when processing USB Request Blocks within the interrupt endpoint management functionality. The flaw occurs in the alloc_mtk_intr_urb function where proper resource cleanup is not performed when btmtk_isopkt_pad() encounters an error condition.
The technical implementation involves the MediaTek Bluetooth driver's USB communication layer where URB structures are dynamically allocated to handle interrupt transfers from Bluetooth devices. When the btmtk_isopkt_pad() function fails during packet padding operations, the driver fails to execute usb_free_urb() on previously allocated URB structures before returning the error code. This creates a memory leak scenario where kernel memory becomes permanently unavailable for reuse, as the URB structures remain allocated in kernel space without proper deallocation.
From an operational perspective this vulnerability represents a denial of service risk that can accumulate over time through repeated error conditions. The memory leak progressively consumes available kernel heap space, potentially leading to system instability or complete system hangs when the kernel memory pool becomes exhausted. Attackers could exploit this by repeatedly triggering Bluetooth communication errors, causing progressive memory consumption until system resources are depleted.
The vulnerability maps directly to CWE-401: "Improper Release of Memory Before Removing Last Reference" which classifies memory management flaws in kernel drivers where allocated resources are not properly freed during error paths. This aligns with ATT&CK technique T1547.001: "Registry Run Keys / Startup Folder" through potential system instability leading to service failures, though the direct attack vector is more focused on resource exhaustion rather than persistence mechanisms.
Mitigation strategies include applying the kernel patch that ensures usb_free_urb() is called before error return in the alloc_mtk_intr_urb function. System administrators should prioritize updating kernel versions containing this fix, particularly in embedded systems or devices where Bluetooth functionality is critical. Additionally implementing memory monitoring tools to detect unusual kernel memory consumption patterns can help identify potential exploitation of this vulnerability. The fix follows standard kernel programming practices for resource management and error handling that aligns with Linux kernel development guidelines for proper cleanup during error conditions.