CVE-2021-0707 in Android
Summary
by MITRE • 04/12/2022
In dma_buf_release of dma-buf.c, there is a possible memory corruption due to a use after free. 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-155756045References: Upstream kernel
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Analysis
by VulDB Data Team • 08/17/2025
The vulnerability identified as CVE-2021-0707 resides within the Android kernel's dma-buf subsystem, specifically in the dma_buf_release function located in dma-buf.c. This represents a critical use-after-free condition that can potentially be exploited for local privilege escalation. The flaw occurs when the kernel attempts to release a dma_buf object, creating a scenario where memory that has already been freed is accessed or modified, leading to unpredictable behavior and memory corruption. Such vulnerabilities are particularly dangerous because they can be leveraged by malicious actors to gain elevated privileges within the system. The vulnerability affects Android kernel versions and was assigned Android ID A-155756045, indicating its severity and the need for immediate attention. The upstream kernel references suggest that this issue has been identified and addressed in the mainline kernel development, but affected Android devices may still be vulnerable until proper patches are applied.
The technical implementation of this vulnerability stems from improper memory management within the dma-buf framework, which is designed to facilitate efficient memory sharing between different kernel components and device drivers. When a dma_buf object is released, the kernel should properly handle the cleanup process to ensure that all references to the memory are properly invalidated and that the memory is safely deallocated. However, in this case, the dma_buf_release function fails to properly manage the object lifecycle, creating a window where freed memory can still be accessed. This use-after-free condition typically occurs when the kernel maintains references to objects that have already been freed or when the cleanup process does not properly invalidate all pointers to the freed memory. The vulnerability is classified under CWE-416, which specifically addresses the use of freed memory issue. According to ATT&CK framework, this vulnerability maps to T1068, which covers "Exploitation for Privilege Escalation" and T1543, which covers "Create or Modify System Process" as attackers could leverage this to modify kernel processes or create malicious ones with elevated privileges.
The operational impact of CVE-2021-0707 is severe for Android devices, as it enables local privilege escalation without requiring any additional execution privileges or user interaction for exploitation. This means that any user with access to the device can potentially exploit this vulnerability to gain root-level privileges, making it particularly dangerous for mobile devices where users may have limited security awareness. The local nature of the exploit suggests that it could be leveraged through malicious applications or compromised system components that are already running on the device. The vulnerability's impact extends beyond simple privilege escalation as it could potentially allow attackers to modify system files, install malicious software, access sensitive data, or even disable security features. The fact that no user interaction is required makes this vulnerability particularly concerning for mobile environments where users may unknowingly expose themselves to attacks through seemingly benign applications. The memory corruption resulting from this use-after-free condition can lead to system instability, crashes, or more sophisticated exploitation techniques that could ultimately result in complete system compromise. Organizations deploying Android devices should be particularly vigilant about this vulnerability as it represents a fundamental flaw in the kernel's memory management that could be exploited to undermine the entire security architecture of the device.