CVE-2026-72489 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
staging: nvec: fix use-after-free in nvec_rx_completed()
In nvec_rx_completed(), when an incomplete RX transfer is detected, nvec_msg_free() is called to return the message back to the pool by clearing its 'used' atomic flag. Immediately after this, the code accesses nvec->rx->data[0] to check the message type.
Since nvec_msg_free() marks the pool slot as available via atomic_set(), any concurrent or subsequent call to nvec_msg_alloc() could claim that same slot and overwrite its data[] array. Reading nvec->rx->data[0] after
freeing the message is therefore a use-after-free.
Fix this by saving the message type byte before calling nvec_msg_free(), then using the saved value for the battery quirk check.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability exists within the Linux kernel's staging driver for nvec devices, specifically in the nvec_rx_completed() function where a classic use-after-free condition occurs. This flaw represents a critical memory safety issue that can lead to system instability and potential privilege escalation. The problem manifests when processing incomplete receive transfers where the driver attempts to free a message structure and immediately access data from the same memory location. According to CWE-416, this constitutes a use-after-free vulnerability where memory is accessed after it has been freed, creating opportunities for undefined behavior and exploitation.
The technical implementation flaw occurs in the sequence of operations within nvec_rx_completed() function where nvec_msg_free() is invoked to return a message to the allocation pool by clearing its 'used' atomic flag. This action makes the memory slot available for reuse by subsequent allocation requests. However, immediately after this freeing operation, the code attempts to read from nvec->rx->data[0] to determine message type for battery quirk checks. The timing window between freeing the memory and accessing it creates a race condition where concurrent or subsequent calls to nvec_msg_alloc() can claim the same memory slot and overwrite its data array contents. This scenario directly violates the fundamental principle of memory safety in kernel space operations.
The operational impact of this vulnerability extends beyond simple system crashes or hangs, potentially enabling attackers to execute arbitrary code with kernel privileges. When an attacker can control the timing of message processing and allocation requests, they may manipulate the overwritten memory contents to influence program flow or inject malicious data structures. The vulnerability affects systems using nvec staging drivers, particularly those managing battery status reporting through the nvec protocol interface. According to ATT&CK framework, this represents a privilege escalation vector through kernel memory corruption techniques that can be leveraged to gain elevated system access.
The fix implemented addresses the root cause by introducing a pre-save mechanism before calling nvec_msg_free(). The solution involves capturing the message type byte from nvec->rx->data[0] immediately before freeing the message structure, then using this saved value for the battery quirk check logic. This approach eliminates the race condition by ensuring that all necessary data is preserved before memory deallocation occurs. The mitigation aligns with secure coding practices recommended in industry standards and kernel development guidelines, specifically addressing the temporal coupling issue between memory deallocation and subsequent access patterns. This defensive programming technique prevents the use-after-free scenario while maintaining the functional integrity of the battery quirk detection mechanism that relies on message type identification for proper device behavior management.