CVE-2026-53294 in Linux
Summary
by MITRE • 06/26/2026
In the Linux kernel, the following vulnerability has been resolved:
mailbox: mailbox-test: don't free the reused channel
The RX channel can be aliased to the TX channel if it has a different MMIO. This special case needs to be handled when freeing the channels otherwise a double-free occurs.
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Analysis
by VulDB Data Team • 06/27/2026
This vulnerability exists within the Linux kernel's mailbox subsystem, specifically in the mailbox-test component that handles communication between different processing units through mailbox channels. The issue stems from improper memory management when dealing with channel reuse scenarios where receive and transmit channels may share identical memory-mapped I/O regions. When the kernel attempts to free these channels during cleanup operations, it fails to properly distinguish between aliased channels that reference the same underlying hardware resources.
The technical flaw manifests when the RX channel is configured to use a different MMIO address space compared to the TX channel, creating a scenario where both channels can reference the same physical mailbox hardware. During normal operation, this aliasing may be acceptable, but during resource deallocation the kernel's memory management code does not account for this special case, leading to attempts to free the same memory region twice. This double-free condition represents a critical memory corruption vulnerability that can potentially lead to system instability or arbitrary code execution.
The operational impact of this vulnerability extends beyond simple memory corruption as it affects the reliability of inter-processor communication mechanisms within embedded systems and multi-core architectures where mailbox interfaces are commonly employed. The vulnerability specifically targets the kernel's mailbox subsystem which is fundamental to communication between different cores, processors, or specialized hardware units in systems such as automotive electronics, network infrastructure devices, and industrial control systems. When exploited, this double-free condition could enable attackers to corrupt kernel memory structures, potentially leading to privilege escalation or system crashes that compromise the entire platform's security posture.
Mitigation strategies should focus on implementing proper channel aliasing detection within the mailbox-test subsystem during resource deallocation phases. The fix requires modifying the channel cleanup logic to identify when RX and TX channels reference identical MMIO regions and prevent duplicate freeing operations through proper reference counting or state tracking mechanisms. This approach aligns with common security practices for preventing double-free vulnerabilities and should be implemented in accordance with established kernel security guidelines. The vulnerability demonstrates the importance of careful resource management in kernel space where improper handling of shared resources can lead to critical security flaws, making it particularly relevant to the CWE-415 and CWE-416 categories that address memory management errors and improper cleanup operations within kernel contexts.
The fix should be implemented with consideration for the ATT&CK framework's system hardening principles, ensuring that kernel-level memory management is robust against exploitation attempts. This vulnerability highlights the need for comprehensive testing of edge cases in kernel subsystems, particularly those involving hardware resource sharing and complex memory management scenarios. Given its potential to affect kernel stability and security, this fix should be prioritized in security updates for embedded systems and multi-core platforms where mailbox interfaces are actively utilized, as it represents a fundamental flaw in the kernel's resource handling capabilities that could be exploited by attackers with access to system resources or privileged execution contexts.