CVE-2020-0431 in Android
Summary
by MITRE
In kbd_keycode of keyboard.c, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-144161459
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/10/2025
The vulnerability identified as CVE-2020-0431 resides within the Android kernel's keyboard input handling subsystem, specifically in the kbd_keycode function located in keyboard.c. This flaw represents a critical security weakness that could enable local privilege escalation without requiring any additional execution privileges or user interaction for exploitation. The vulnerability is classified as an out-of-bounds write condition that occurs due to the absence of proper bounds checking mechanisms within the kernel's input processing code.
The technical root cause of this vulnerability stems from inadequate input validation within the keyboard subsystem where the kbd_keycode function fails to verify that incoming keycode values remain within acceptable memory boundaries. When processing keyboard input events, the function attempts to write data to memory locations without ensuring that these locations are properly allocated and accessible, creating a scenario where malicious input could overwrite adjacent memory regions. This type of flaw falls under the CWE-129 category of Improper Validation of Array Index, which is a well-documented weakness in software security that directly contributes to buffer overflow conditions. The vulnerability's impact is amplified by its location within the kernel space, where any memory corruption can potentially lead to system instability or complete compromise of the device's security model.
From an operational perspective, this vulnerability presents a significant risk to Android devices as it allows for local privilege escalation without requiring user interaction or additional privileges. An attacker with local access to a device could exploit this vulnerability to gain elevated privileges and potentially execute arbitrary code with kernel-level permissions. The lack of user interaction requirements makes this particularly dangerous as it can be exploited automatically when keyboard events are processed, such as during normal device operation or when input is received through various input methods. This vulnerability directly aligns with the ATT&CK framework's privilege escalation techniques, specifically targeting the T1068 - Steal or Modify Tools section where adversaries may exploit kernel-level weaknesses to gain elevated access. The Android ID A-144161459 indicates this was properly tracked and addressed within the Android security framework, highlighting the severity of the issue.
Mitigation strategies for CVE-2020-0431 should focus on immediate patching of affected Android kernel versions and implementation of robust input validation mechanisms. System administrators should ensure that all Android devices receive the appropriate security updates that address this specific kernel vulnerability. The fix typically involves adding proper bounds checking to the kbd_keycode function to verify that input values remain within valid memory boundaries before any write operations occur. Additionally, organizations should implement monitoring for unusual keyboard input patterns that might indicate exploitation attempts, though the nature of this vulnerability means that exploitation occurs at the kernel level where such monitoring becomes more complex. Regular security audits of kernel components and input handling subsystems should be conducted to identify similar vulnerabilities that might exist in other parts of the system architecture, particularly focusing on the CWE-787 - Out-of-bounds Write category which encompasses this specific weakness. The vulnerability's classification as a kernel-level issue also necessitates comprehensive testing of patch effectiveness and monitoring for potential side effects on device functionality.