CVE-2023-21065 in Android
Summary
by MITRE • 03/24/2023
In fdt_next_tag of fdt.c, there is a possible out of bounds write due to an integer overflow. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-239630493References: N/A
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Analysis
by VulDB Data Team • 09/10/2025
The vulnerability identified as CVE-2023-21065 resides within the flattened device tree (FDT) implementation of the Android kernel, specifically in the fdt_next_tag function located in fdt.c. This flaw represents a critical security issue that could enable local privilege escalation, requiring only system execution privileges for exploitation. The vulnerability manifests as a potential out of bounds write condition that stems from an integer overflow within the device tree parsing logic, making it particularly dangerous in kernel-level contexts where memory corruption can lead to severe system compromise.
The technical root cause of this vulnerability lies in the improper handling of integer values during device tree tag traversal operations. When processing device tree structures, the fdt_next_tag function performs calculations that can result in integer overflow conditions, leading to miscalculations in memory access boundaries. This overflow condition allows an attacker to manipulate the device tree parsing logic into writing data beyond the allocated memory boundaries, creating opportunities for memory corruption that can be exploited to gain elevated privileges. The vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which is a well-documented class of flaws that frequently leads to memory corruption vulnerabilities.
The operational impact of CVE-2023-21065 extends beyond simple memory corruption as it provides a pathway for local privilege escalation within the Android kernel environment. Since the exploit requires only system execution privileges, it can be leveraged by malicious applications or processes already running with kernel-level access to elevate their privileges further. This makes the vulnerability particularly concerning in environments where applications might have been granted system-level permissions or where privilege escalation opportunities exist. The lack of user interaction requirement means that exploitation can occur automatically without any additional user consent or intervention, making it a stealthy and potentially devastating security flaw.
Mitigation strategies for this vulnerability should focus on implementing proper integer overflow checks within the device tree parsing logic, particularly in the fdt_next_tag function. The recommended approach involves adding bounds checking mechanisms that validate integer calculations before memory operations occur, ensuring that calculated offsets remain within valid memory boundaries. Additionally, kernel hardening techniques such as stack canaries, address space layout randomization, and kernel address space layout randomization should be enabled to complicate exploitation attempts. The Android security team should prioritize patching this vulnerability through kernel updates and ensure that all affected Android versions receive timely security updates. Organizations should also implement monitoring for suspicious kernel-level activities that might indicate exploitation attempts, as the vulnerability could be used as a stepping stone for more extensive system compromise. This vulnerability aligns with ATT&CK technique T1068 which involves exploiting vulnerabilities to gain system privileges, making it a critical target for both defensive and offensive security teams to address.