CVE-2019-18874 in python-psutil
Summary
by MITRE
psutil (aka python-psutil) through 5.6.5 can have a double free. This occurs because of refcount mishandling within a while or for loop that converts system data into a Python object.
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Analysis
by VulDB Data Team • 02/11/2024
The vulnerability identified as CVE-2019-18874 affects psutil version 5.6.5 and earlier, representing a critical double free condition that stems from improper reference counting management within Python object conversion processes. This issue specifically manifests when system data is being converted into Python objects within iterative control structures such as while or for loops, creating a scenario where memory management becomes compromised due to incorrect handling of object reference counts.
The technical flaw resides in the psutil library's internal memory management mechanisms where the reference counting system fails to properly track object lifecycle during data conversion operations. When system information is processed and transformed into Python objects within looping constructs, the library's garbage collection logic incorrectly manages object references, leading to situations where the same memory location may be freed twice. This represents a classic double free vulnerability that can result in memory corruption and potentially arbitrary code execution.
The operational impact of this vulnerability extends beyond simple memory corruption as it can enable attackers to manipulate the memory layout of the affected application. When the double free occurs during system data processing, it creates opportunities for heap-based attacks where malicious actors could potentially control the freed memory locations to inject and execute arbitrary code. The vulnerability is particularly concerning because psutil is widely used across various applications for system monitoring and resource management, making the attack surface expansive.
This vulnerability maps to CWE-415: Double Free within the Common Weakness Enumeration framework, specifically addressing improper memory management in Python extension modules. The issue demonstrates a failure in proper reference counting practices that should be maintained when working with Python's C API and object lifecycle management. From an ATT&CK perspective, this vulnerability aligns with T1059.001: Command and Scripting Interpreter: Python, as it affects Python applications that utilize psutil for system information gathering, and could enable T1078: Valid Accounts through potential privilege escalation scenarios.
Mitigation strategies for CVE-2019-18874 require immediate patching of affected psutil versions to 5.6.6 or later, which contains the necessary fixes for the reference counting logic. System administrators should also implement monitoring for unusual memory allocation patterns and potential heap corruption indicators. Additionally, applications using psutil should be audited for proper error handling and memory management practices, particularly in areas where system data conversion occurs within loops. The vulnerability underscores the importance of thorough testing of memory management code in Python extensions and the need for comprehensive security reviews of system monitoring libraries that operate at privileged levels.