CVE-2021-32273 in FAAD2
Summary
by MITRE • 09/20/2021
An issue was discovered in faad2 through 2.10.0. A stack-buffer-overflow exists in the function ftypin located in mp4read.c. It allows an attacker to cause Code Execution.
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Analysis
by VulDB Data Team • 08/30/2025
The vulnerability identified as CVE-2021-32273 represents a critical stack buffer overflow condition within the faad2 library version 2.10.0 and earlier. This issue resides in the ftypin function within the mp4read.c source file, creating a potential pathway for remote code execution through maliciously crafted media files. The flaw demonstrates characteristics consistent with CWE-121 Stack-based Buffer Overflow, where insufficient bounds checking allows data to overwrite adjacent memory locations on the stack. The affected library serves as a core component in audio decoding operations for various multimedia applications and operating systems, making the vulnerability particularly concerning for widespread exploitation.
The technical implementation of this vulnerability stems from inadequate input validation within the function that processes mp4 file headers and metadata. When processing malformed or specially crafted mp4 files, the ftypin function fails to properly validate buffer boundaries during the parsing of file type identifiers and related metadata structures. This allows an attacker to supply input data that exceeds the allocated stack buffer space, resulting in memory corruption that can be leveraged to overwrite return addresses and function pointers. The vulnerability's exploitation potential aligns with ATT&CK technique T1203 Exploitation for Client Execution, as it enables arbitrary code execution when vulnerable applications process malicious media files.
The operational impact of this vulnerability extends across numerous software ecosystems that depend on faad2 for audio processing capabilities. Applications ranging from media players and streaming services to embedded systems and mobile platforms that utilize this library for decoding advanced audio formats become susceptible to remote code execution attacks. The vulnerability's severity is amplified by the fact that it can be triggered through normal media file processing operations without requiring special privileges or user interaction. Attackers can craft malicious mp4 files that, when processed by vulnerable applications, will cause the stack buffer overflow and subsequent code execution. This creates a significant risk for both individual users and enterprise environments where multimedia content processing is common.
Mitigation strategies for CVE-2021-32273 primarily focus on immediate software updates and patches provided by the maintainers of the faad2 library. Organizations should prioritize upgrading to version 2.10.1 or later, which contains the necessary fixes for the buffer overflow condition. Additionally, implementing input validation controls and sandboxing mechanisms around media file processing can provide defense-in-depth measures. Network-based mitigations such as content filtering and media file scanning can help prevent exploitation attempts through malicious file uploads or downloads. System administrators should also consider implementing runtime protections and monitoring for suspicious memory access patterns that may indicate exploitation attempts. The vulnerability's classification as a stack buffer overflow makes it particularly susceptible to exploit prevention techniques such as stack canaries, address space layout randomization, and compiler-based protections that can significantly reduce the exploitability of such flaws.