A heap-based buffer overflow vulnerability (CVE-2026-51273) has been identified in schreibfaul1 ESP32-audioI2S version 3.4.5, an embedded audio streaming library for ESP32 microcontrollers. The flaw resides in the ID3 tag parsing function showID3Tag(), which uses an unbounded appendf() call to write formatted strings into a heap buffer (ps_ptr) without performing any length validation. Attackers can exploit this vulnerability by crafting malicious audio files containing excessively long ID3 tag values. Successful exploitation may result in arbitrary code execution, sensitive memory data leakage, device crashes, or privilege escalation. The vulnerability poses a significant risk to IoT and embedded devices running the affected library version. No patch information is noted in the article, and the issue was submitted to NVD.