Heap-based Buffer Overflow in schreibfaul1 ESP32-audioI2S

Executive Summary

This is a heap-based buffer overflow in the schreibfaul1 ESP32-audioI2S library version 3.4.5. The vulnerability occurs in the URL path handling where untrusted query strings are appended to a base URL without length checks. When these strings are passed to the urlencode function, the encoded output can expand significantly, overflowing a fixed-size heap buffer in PSRAM. This leads to memory corruption, potentially causing crashes, code execution, or information disclosure.

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Detection Guidance

To detect this vulnerability, monitor network traffic for unusually long query strings in audio stream URLs. Use tools like Wireshark or tcpdump to capture and inspect HTTP requests targeting ESP32 devices. Check for crashes or freezes in audio streaming services after connecting to suspicious URLs.

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Impact Analysis

The vulnerability allows remote attackers to crash the ESP32 audio streaming service via a specially crafted URL, causing denial of service or watchdog reboots. It may also enable arbitrary code execution or expose sensitive memory data like audio and network runtime information. Exploitation requires only that the device connects to a malicious audio stream URL.

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Compliance Impact

This vulnerability could lead to unauthorized memory access, potentially exposing sensitive data such as audio streams or network runtime information. This may violate GDPR's data protection principles if personal data is leaked, and HIPAA's security requirements if protected health information is compromised. The denial of service impact could also disrupt critical services, affecting compliance with availability requirements.

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Mitigation Strategies

Immediately restrict untrusted input in audio stream URLs by implementing strict length limits on query strings. Update network firewalls to block excessively long URLs. Consider disabling automatic audio stream connections until a patch is released.

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