CVE-2022-20239 in Android
Summary
by MITRE • 08/11/2022
'remap_pfn_range' here may map out of size kernel memory (for example, may map the kernel area), and because the 'vma->vm_page_prot' can also be controlled by userspace, so userspace may map the kernel area to be writable, which is easy to be exploitedProduct: AndroidVersions: Android SoCAndroid ID: A-233972091
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Analysis
by VulDB Data Team • 10/20/2025
The vulnerability described in CVE-2022-20239 represents a critical kernel memory management flaw within Android systems that stems from improper validation in the remap_pfn_range function. This function serves as a crucial interface for mapping physical page frame numbers to virtual memory areas, but the implementation contains a fundamental oversight that allows userspace processes to manipulate kernel memory mappings. The vulnerability specifically arises from the lack of proper bounds checking when mapping kernel memory regions, enabling malicious userspace code to potentially access and modify protected kernel areas that should remain inaccessible to user processes.
The technical exploitation mechanism relies on the ability of userspace to control the vma->vm_page_prot field, which defines the memory protection attributes for virtual memory areas. When combined with the flawed remap_pfn_range implementation, this creates a scenario where userspace can map kernel memory regions with writable permissions, effectively breaking the fundamental kernel memory protection boundaries. This represents a classic case of improper input validation and privilege escalation, where user-mode code gains the ability to manipulate kernel memory mappings through controlled manipulation of virtual memory area parameters. The vulnerability exists in Android SoC implementations and was identified through Android ID A-233972091, indicating its presence in specific mobile processor architectures.
The operational impact of this vulnerability is severe as it enables arbitrary code execution within kernel space, potentially allowing attackers to escalate privileges from user mode to kernel mode. Successful exploitation could result in complete system compromise, persistent backdoor installation, or data exfiltration from protected kernel memory regions. The vulnerability affects Android devices running on specific SoC architectures, making it particularly concerning for mobile security as it undermines the core security model that separates user and kernel space execution environments. This type of vulnerability directly violates the principle of least privilege and can be leveraged to bypass various security mechanisms including kernel address space layout randomization and other exploit mitigations.
Mitigation strategies for CVE-2022-20239 should focus on strengthening the validation mechanisms within the remap_pfn_range function and implementing proper bounds checking for kernel memory mappings. System administrators and device manufacturers should prioritize applying security patches that restrict userspace control over memory protection attributes and implement additional checks to prevent mapping of kernel memory regions. The vulnerability aligns with CWE-122 (Heap Overflow) and CWE-787 (Out-of-bounds Write) categories, and can be categorized under ATT&CK technique T1068 (Local Privilege Escalation) and T1059 (Command and Scripting Interpreter). Regular security updates and kernel hardening measures are essential to prevent exploitation, along with monitoring for suspicious memory mapping activities that could indicate attempted exploitation of this vulnerability.