CVE-2026-68423 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
mtd: virt_concat: fix use-after-free in mtd_virt_concat_destroy()
mtd_concat_destroy() frees item->concat so calling mtd_virt_concat_put_mtd_devices(item->concat) after that leads to a use-after-free.
Fix it by moving mtd_virt_concat_put_mtd_devices() before mtd_concat_destroy().
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability resides within the Linux kernel's memory technology device subsystem, specifically in the virtual concatenation functionality that manages multiple MTD devices as a single logical unit. This issue manifests as a use-after-free condition during the destruction process of virtual concatenated MTD devices, representing a critical memory safety flaw that can potentially lead to system instability or arbitrary code execution. The problem occurs in the mtd_virt_concat_destroy() function where improper ordering of cleanup operations creates a temporal window for memory access violations.
The technical flaw stems from a sequence of function calls that violates proper resource management principles within the kernel's device management framework. When mtd_concat_destroy() is invoked, it frees the memory associated with item->concat structure, but subsequent execution of mtd_virt_concat_put_mtd_devices(item->concat) attempts to access the same freed memory region. This fundamental ordering issue creates a use-after-free vulnerability that allows attackers to potentially corrupt kernel memory or execute malicious code by manipulating the MTD device concatenation process. The flaw demonstrates poor defensive programming practices and inadequate memory lifecycle management.
The operational impact of this vulnerability extends beyond simple system crashes, as it represents a potential vector for privilege escalation attacks within kernel space. Attackers could exploit this condition to manipulate kernel memory structures, potentially leading to denial of service scenarios or more severe compromise of the system's integrity. The vulnerability affects systems that utilize virtual concatenated MTD devices, which are commonly found in embedded systems, flash storage management, and various IoT device configurations where multiple flash memory components are logically unified. This makes the impact widespread across numerous Linux-based platforms that rely on proper MTD subsystem functionality.
Mitigation strategies must focus on correcting the function call ordering within the kernel source code to ensure that mtd_virt_concat_put_mtd_devices() is executed before mtd_concat_destroy() completes its memory deallocation. The fix aligns with established security best practices for kernel development and memory management, ensuring proper resource cleanup order and preventing temporal memory access violations. This vulnerability resolution demonstrates the importance of maintaining strict ordering in kernel-level operations and adheres to common CWE guidelines for memory safety issues while potentially mapping to ATT&CK techniques related to privilege escalation and kernel exploitation through memory corruption vulnerabilities.