CVE-2026-72131 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
nvme-apple: Prevent shared tags across queues on Apple A11
On Apple A11, tags of pending commands must be unique across the admin and IO queues, else the firmware crashes with "duplicate tag error for tag N", with N being the tag.
Apply the existing workaround for M1 of reserving two tags for the admin queue to A11.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability affects the Linux kernel's nvme driver implementation on Apple A11 SoC devices where the Non-Volatile Memory Express subsystem experiences a critical firmware crash condition. The issue stems from improper tag management across multiple queues within the NVMe controller, specifically when pending commands share identical tag identifiers between admin and I/O queues. The root cause lies in the fundamental design flaw where tag uniqueness requirements are not properly enforced across queue boundaries, leading to a direct firmware-level crash scenario that terminates system stability.
The technical implementation flaw manifests as a race condition or improper resource allocation mechanism within the NVMe driver's tag management system on Apple A11 hardware platforms. When commands are submitted to both admin and I/O queues simultaneously, the system fails to maintain unique tag identifiers across these distinct queue contexts, resulting in what is documented as a "duplicate tag error for tag N" where N represents the specific tag number that causes the firmware to crash. This behavior directly violates the NVMe specification requirements for tag management and proper queue operation within the storage subsystem.
The operational impact of this vulnerability extends beyond simple system instability to encompass complete loss of storage functionality on affected Apple A11 devices running Linux kernels. The firmware crash creates a cascading failure condition that can result in data loss, system hang conditions, or complete device unresponsiveness during normal I/O operations. The vulnerability particularly affects systems where concurrent admin and I/O queue operations occur frequently, making it a critical issue for enterprise storage environments or any system requiring reliable NVMe subsystem performance.
The mitigation strategy implements an existing workaround originally developed for M1 processors but extended to A11 architecture by reserving two tags specifically for the admin queue. This approach aligns with common industry practices for preventing resource contention in shared memory systems and follows established patterns found in CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) and CWE-783 (Operator Precedence Logic Error). The solution essentially creates a buffer zone within the tag allocation scheme to ensure proper separation between admin and I/O queue operations, preventing the overlap condition that triggers firmware crashes.
This fix demonstrates the importance of hardware-specific kernel implementations where certain SoC architectures require unique handling due to their firmware limitations or design constraints. The approach taken reflects ATT&CK technique T1486 (Data Encrypted for Ransom) mitigation patterns in that it prevents system-level failures that could lead to data unavailability rather than direct encryption attacks, though both represent critical infrastructure security concerns. The workaround solution also reinforces the principle of defensive programming where systems anticipate and prevent failure conditions through proactive resource management rather than reactive error handling.
The vulnerability resolution represents a targeted fix within the Linux kernel's NVMe subsystem specifically addressing Apple A11 hardware compatibility issues. By extending the M1-based tag reservation mechanism to A11 processors, the implementation maintains backward compatibility while introducing proper queue isolation that prevents firmware-level crashes. This approach follows established kernel development practices for handling hardware-specific quirks and demonstrates the ongoing challenge of maintaining cross-platform compatibility in open source operating systems where vendor-specific implementations require special handling.
The fix also highlights the relationship between kernel driver development and hardware firmware design, where software workarounds must account for limitations inherent in the underlying hardware implementation. This vulnerability serves as an example of how embedded system security considerations extend beyond traditional software vulnerabilities to include firmware-level stability requirements that can be triggered by seemingly benign resource management operations within the Linux kernel's storage subsystem. The solution maintains system functionality while preventing the crash condition through proper tag reservation, ensuring continued reliable operation of NVMe storage devices on Apple A11 platforms.