Buffer Overflow in Schreibfaul1 ESP32-audioI2S

Executive Summary

This is a heap buffer overflow vulnerability in the ESP32-audioI2S library version 3.4.5. It occurs in the MP3Decoder::decode() function where attacker-controlled values from malicious MP3 files are used without proper size validation before memory copy operations. The issue stems from unsafe use of memmove and memcpy on the m_MP3DecInfo mainBuf heap buffer, allowing writes beyond allocated memory when processing oversized parameters.

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Detection Guidance

Detecting this vulnerability requires analyzing MP3 files processed by the ESP32-audioI2S library. Check for crashes or freezes when loading MP3 files, especially those with manipulated headers. Use static analysis tools to inspect MP3 decoder code for missing bounds checks on mainDataBegin and nSlots values. Monitor heap memory usage for unexpected spikes during MP3 decoding.

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Impact Analysis

Exploitation could lead to remote denial of service by crashing the device or freezing the audio service. In some cases, it may allow arbitrary code execution on ESP32 hardware running the affected library. An attacker only needs to trick the victim into loading a specially crafted MP3 file.

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Compliance Impact

This vulnerability primarily impacts device reliability and security by enabling remote denial of service or arbitrary code execution through crafted MP3 files. For compliance standards like GDPR or HIPAA, which require data integrity and system availability, this flaw could lead to unauthorized access or disruption of audio processing services, potentially violating confidentiality or availability requirements if exploited.

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Mitigation Strategies

Immediately upgrade to a patched version of ESP32-audioI2S if available. If not, disable MP3 decoding functionality or restrict input to trusted MP3 files. Implement strict input validation for MP3 headers, particularly mainDataBegin and nSlots values. Add runtime bounds checking before memory copy operations in the decoder.

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