CVE-2026-68479 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: btrtl: validate firmware patch bounds
rtlbt_parse_firmware() copies patch_length - 4 bytes before appending the firmware version. A malformed firmware patch shorter than the version field can make this subtraction underflow and turn the copy into an oversized read and write during Bluetooth setup.
The existing patch_offset + patch_length check can also wrap on 32-bit architectures. Validate the patch length and range without arithmetic overflow before allocating or copying the patch.
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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 btrtl driver responsible for handling Realtek Bluetooth controllers. The issue stems from inadequate validation of firmware patch boundaries during the firmware parsing process, creating a potential for memory corruption and arbitrary code execution. The flaw manifests when the rtlbt_parse_firmware() function processes incoming firmware patches without proper bounds checking, leading to critical security implications that could compromise system integrity.
The technical implementation of this vulnerability exploits integer underflow conditions in the firmware processing logic. When a malformed firmware patch is presented to the system, the function attempts to subtract four bytes from the patch_length value before appending the firmware version field. If the firmware patch is shorter than four bytes, this arithmetic operation results in an underflow condition that produces a very large unsigned integer value. This invalid length then gets used as the copy size parameter in subsequent memory operations, causing what appears to be an oversized read and write during Bluetooth initialization. The vulnerability specifically impacts 32-bit architectures where the patch_offset + patch_length calculation can also wrap around due to limited integer precision, creating additional attack vectors.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling remote code execution within the kernel space. An attacker who can supply a specially crafted firmware patch could leverage this flaw to overwrite critical kernel memory locations, bypass security controls, and establish persistent access to affected systems. This represents a severe privilege escalation vector since the Bluetooth subsystem typically runs with elevated privileges during device initialization. The vulnerability affects all Linux systems utilizing Realtek Bluetooth controllers that employ the btrtl driver, making it particularly concerning for mobile devices, laptops, and embedded systems where Bluetooth connectivity is prevalent.
Mitigation strategies should focus on implementing comprehensive bounds checking before any memory allocation or copy operations occur in the firmware parsing pipeline. The recommended approach involves validating patch_length values against maximum allowable sizes and ensuring all arithmetic operations use proper overflow detection mechanisms. System administrators should prioritize applying kernel updates that include the patched btrtl driver implementation, which incorporates checks to prevent underflow conditions and wrap-around scenarios on 32-bit systems. Additionally, organizations should consider implementing runtime monitoring for suspicious Bluetooth firmware loading activities and maintain regular security assessments of their Linux kernel configurations. This vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and potentially maps to ATT&CK technique T1059.008 for execution through kernel exploits, emphasizing the need for layered defensive measures.
This flaw demonstrates the critical importance of proper input validation in kernel-level drivers where memory safety directly impacts system security. The vulnerability highlights how seemingly minor arithmetic operations can create devastating security implications when not properly protected against overflow conditions. The patch implementation must ensure all firmware processing operations include comprehensive bounds checking that prevents any scenario where user-supplied data could cause integer underflow or overflow, particularly in contexts involving memory allocation and copy operations.