CVE-2016-3826 in Android
Summary
by MITRE
services/audioflinger/Effects.cpp in mediaserver in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-08-01 does not validate the reply size for an AudioFlinger effect command, which allows attackers to gain privileges via a crafted application, aka internal bug 29251553.
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Analysis
by VulDB Data Team • 09/13/2025
The vulnerability described in CVE-2016-3826 resides within the Android media server component known as AudioFlinger, specifically in the Effects.cpp file that handles audio effect processing. This flaw represents a critical privilege escalation vulnerability affecting multiple Android versions including 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before the specified date. The issue stems from inadequate validation of reply sizes during AudioFlinger effect command processing, creating a potential attack vector that allows malicious applications to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability involves a buffer overflow condition that occurs when the mediaserver process fails to properly validate the size of responses received from audio effect commands. This validation failure creates an opportunity for attackers to craft specially designed applications that send malformed reply data structures. When the AudioFlinger component processes these crafted responses, it does not properly bounds-check the data size, leading to memory corruption that can be exploited to execute arbitrary code with system-level privileges. The vulnerability operates at the kernel level within the Android media framework, making it particularly dangerous as it can bypass normal application sandboxing mechanisms.
The operational impact of this vulnerability is severe as it enables attackers to escalate privileges from regular application context to system-level access without requiring physical device access or user interaction. This privilege escalation allows malicious actors to gain complete control over the device, potentially enabling data theft, persistent backdoor installation, and full system compromise. The vulnerability affects a wide range of Android devices spanning multiple major versions, making it particularly attractive to attackers seeking broad exploitation coverage. The issue represents a classic example of a buffer overflow vulnerability that can be leveraged for privilege escalation, with the specific attack vector targeting the audio subsystem's command processing mechanism.
From a cybersecurity perspective, this vulnerability maps directly to CWE-129, which describes improper validation of the length of input data, and aligns with ATT&CK technique T1068, which covers exploit for privilege escalation. The vulnerability demonstrates how seemingly isolated subsystems within operating systems can contain critical flaws that affect the entire platform security model. Organizations should implement immediate mitigations including applying the relevant Android security patches released by Google, disabling unnecessary audio effects functionality, and monitoring for suspicious application behavior that might indicate exploitation attempts. The vulnerability also highlights the importance of comprehensive input validation across all system components, particularly those handling inter-process communication and system-level operations. Device manufacturers and security teams should prioritize patch deployment and consider implementing additional runtime protections to prevent exploitation of similar vulnerabilities in the audio subsystem and other system components.