CVE-2026-51259 affects schreibfaul1 ESP32-audioI2S version 3.4.5, an audio library for ESP32 microcontrollers. The vulnerability stems from an unchecked unsigned integer overflow in the buffer size calculation logic, leading to undersized PSRAM buffer allocation. When normal audio buffer read and write operations are subsequently performed, they cause heap out-of-bounds access and memory corruption. The impact ranges from denial of service to potential arbitrary code execution. The flaw resides in the Audio.cpp source file of the library. This is an embedded/IoT platform vulnerability affecting devices using this audio library. No patch version is referenced in the advisory. The vulnerability was disclosed via GitHub advisory and reported to NVD.