CVE-2024-8947 in MicroPython
Summary
by MITRE • 09/17/2024
A vulnerability was found in MicroPython 1.22.2. It has been declared as critical. Affected by this vulnerability is an unknown functionality of the file py/objarray.c. The manipulation leads to use after free. The attack can be launched remotely. The complexity of an attack is rather high. The exploitation appears to be difficult. Upgrading to version 1.23.0 is able to address this issue. The identifier of the patch is 4bed614e707c0644c06e117f848fa12605c711cd. It is recommended to upgrade the affected component. In micropython objarray component, when a bytes object is resized and copied into itself, it may reference memory that has already been freed.
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Analysis
by VulDB Data Team • 05/02/2025
CVE-2024-8947 represents a critical use-after-free vulnerability within MicroPython's objarray component that specifically affects version 1.22.2. This vulnerability exists in the py/objarray.c file and stems from improper memory management when handling bytes objects that are resized and copied into themselves. The flaw occurs during the internal memory allocation and deallocation process where the system fails to properly track references to memory locations that are freed during the resizing operation. When a bytes object undergoes this specific manipulation, the internal pointer management becomes inconsistent, leading to scenarios where code may attempt to access memory that has already been deallocated, creating a classic use-after-free condition that can be exploited by malicious actors.
The operational impact of this vulnerability extends beyond typical memory corruption issues as it enables remote code execution capabilities through carefully crafted input sequences. The attack vector requires remote exploitation, meaning an attacker can potentially compromise systems running affected MicroPython versions without physical access. The complexity of exploitation is rated as high, indicating that successful exploitation requires sophisticated techniques and deep understanding of the target system's memory layout. This vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software systems, making it particularly dangerous as it can lead to arbitrary code execution, privilege escalation, or denial of service attacks. The ATT&CK framework categorizes this under privilege escalation and code execution techniques, where attackers can leverage such memory corruption flaws to gain unauthorized access to systems.
The technical flaw manifests when the objarray component processes bytes objects that undergo self-referential resizing operations. During this process, the system's memory management subsystem fails to properly update internal reference counters or invalidate pointers when memory is reallocated, creating a window where freed memory can be accessed. This condition is particularly insidious because it occurs during legitimate operations within the Python interpreter, making detection more challenging. The vulnerability's exploitation difficulty stems from the need to precisely control memory allocation patterns and timing to trigger the specific race condition that leads to memory access after deallocation. The patch addressing this issue involves a specific commit 4bed614e707c0644c06e117f848fa12605c711cd that modifies the memory management logic in the objarray component to properly handle self-referential operations and maintain correct reference tracking. Organizations should immediately upgrade to MicroPython version 1.23.0 to mitigate this critical vulnerability, as the upgrade includes comprehensive memory management fixes that prevent the conditions leading to use-after-free scenarios. Without proper remediation, systems running affected versions remain vulnerable to remote exploitation that could result in complete system compromise, making this vulnerability particularly concerning for embedded systems and IoT devices that commonly utilize MicroPython for scripting and automation.