CVE-2016-3863 in Android
Summary
by MITRE
Multiple stack-based buffer overflows in the AVCC reassembly implementation in Utils.cpp in libstagefright in MediaMuxer in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, 6.x before 2016-09-01, and 7.0 before 2016-09-01 allow remote attackers to execute arbitrary code via a crafted media file, aka internal bug 29161888.
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Analysis
by VulDB Data Team • 09/13/2025
The vulnerability identified as CVE-2016-3863 represents a critical stack-based buffer overflow within the Android media processing framework, specifically affecting the AVCC reassembly implementation in libstagefright. This flaw exists in the MediaMuxer component of Android operating systems across multiple versions including 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, 6.x before the 2016-09-01 security patch, and 7.0 before the same patch date. The vulnerability stems from improper input validation during the processing of media files, particularly those containing AVC (Advanced Video Coding) content. When a maliciously crafted media file is processed by the affected Android versions, the buffer overflow occurs during the reassembly phase of AVCC data structures, creating a potential execution path for remote attackers.
The technical implementation of this vulnerability involves a stack-based buffer overflow that occurs in the Utils.cpp file within the libstagefright library. During media file processing, the system fails to properly validate the size of incoming AVCC reassembly data, allowing an attacker to provide input that exceeds the allocated buffer space on the stack. This overflow can overwrite adjacent stack memory locations, potentially corrupting program execution flow and enabling arbitrary code execution. The flaw specifically targets the way the system handles variable-length data structures in the AVCC format, where the expected buffer size calculations are insufficient to handle malformed input. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, representing a classic memory corruption vulnerability that has been exploited in numerous mobile platform attacks.
The operational impact of CVE-2016-3863 extends beyond simple code execution, as it provides attackers with a powerful remote exploitation vector that can compromise entire Android devices. The vulnerability affects a core media processing component that is invoked whenever users play or process media files, making it particularly dangerous for widespread exploitation. Attackers can craft malicious media files that trigger the buffer overflow when opened by vulnerable Android devices, potentially gaining full system control without requiring user interaction beyond opening the media. This makes the vulnerability particularly attractive for zero-day exploits and mobile malware distribution. The attack surface is extensive given that media processing is a fundamental Android function, affecting billions of devices globally.
Mitigation strategies for CVE-2016-3863 require immediate system updates and patch deployment across all affected Android versions. Organizations and users must prioritize installing security patches released by Google and device manufacturers, as these updates contain fixed implementations of the AVCC reassembly logic that properly validate buffer sizes. The ATT&CK framework categorizes this vulnerability under T1059.007 for execution through media file manipulation, highlighting the need for network-level monitoring and content filtering. Additional protective measures include implementing mobile device management policies that restrict media file downloads from untrusted sources, enabling automatic security updates, and deploying endpoint protection solutions that can detect and block malicious media files. Network administrators should also consider implementing sandboxing mechanisms for media processing and maintaining detailed monitoring of file access patterns to identify potential exploitation attempts.