CVE-2026-51251 in ESP32-audioI2S
Summary
by MITRE • 07/28/2026
Schreibfaul1 ESP32-audioI2S 3.4.5 has a buffer overflow vulnerability in the MP3Decoder::decode() function of the MP3 decoder due to missing size validation on untrusted mainDataBegin and nSlots values.
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Analysis
by VulDB Data Team • 07/28/2026
The Schreibfaul1 ESP32-audioI2S library version 3.4.5 contains a critical buffer overflow vulnerability within its MP3 decoding component that poses significant security risks to embedded audio applications. This vulnerability specifically affects the MP3Decoder::decode() function where insufficient input validation occurs on two critical parameters: mainDataBegin and nSlots. These values are typically derived from untrusted MP3 file headers and are used to calculate buffer boundaries during audio frame processing. The lack of proper size validation creates an exploitable condition where maliciously crafted MP3 files could trigger memory corruption when the decoder attempts to write data beyond allocated buffer boundaries.
The technical flaw stems from improper bounds checking in the audio decoding logic where the library directly uses values obtained from MP3 file metadata without adequate verification against expected ranges or buffer limits. When mainDataBegin and nSlots contain unexpected large values, the calculation of buffer offsets leads to writes occurring at memory locations outside the intended allocation space. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow and represents a classic case of insufficient input validation in embedded systems processing untrusted media content. The vulnerability is particularly concerning because it operates within the audio decoding pipeline where attackers could potentially craft MP3 files that trigger this condition during normal playback operations, leading to arbitrary code execution or system crashes.
Operationally, this buffer overflow vulnerability creates multiple attack vectors for adversaries targeting ESP32-based audio applications. The impact extends beyond simple denial of service scenarios as the vulnerability could enable remote code execution depending on the specific memory layout and system configuration. Attackers could potentially craft malicious MP3 files that, when processed by vulnerable applications, cause the device to crash or execute unintended code with the privileges of the running application. This presents a serious risk for IoT devices and embedded systems where these libraries are commonly deployed for audio processing tasks. The vulnerability affects any application using the ESP32-audioI2S library version 3.4.5 for MP3 decoding, making it particularly dangerous in environments where users cannot control or validate incoming audio content.
Mitigation strategies should focus on immediate library updates to versions that address the buffer overflow condition through proper input validation and bounds checking. Organizations should implement strict MP3 file validation routines that verify header parameters before processing, particularly focusing on mainDataBegin and nSlots values against reasonable maximum limits. The implementation of defensive programming techniques such as stack canaries, address space layout randomization, and memory protection mechanisms should be considered for additional defense in depth. Security patches should also include runtime checks that validate the integrity of MP3 file headers and implement proper error handling for malformed input data. System administrators should monitor for vulnerable installations and ensure all deployed applications using this library are updated to patched versions that incorporate proper size validation mechanisms, aligning with best practices recommended by the ATT&CK framework for defending against memory corruption vulnerabilities in embedded systems environments.