Executive brief
A vulnerability exists in the ESP32-audioI2S library, which is used to play audio on ESP32 microcontrollers. The software fails to properly check the size of data when converting HTML characters in audio metadata, such as song titles or stream labels. An attacker could send a specially crafted audio stream that causes the device to crash, leak memory information, or potentially allow for remote control of the device.
Technical details
A heap-based buffer overflow exists in the htmlToUTF8() function within src/Audio.cpp of the schreibfaul1 ESP32-audioI2S library. The vulnerability is caused by the use of memmove and memcpy to rearrange decoded HTML entity data into a fixed-size heap buffer (ps_ptr) without validating the remaining buffer capacity or the expansion size of the decoded characters. An unauthenticated remote attacker can trigger this by providing a malicious audio stream or metadata containing oversized numeric or named HTML entities. This results in an out-of-bounds write to PSRAM, leading to a denial of service (watchdog reset), memory leakage, or potential remote code execution. As of the advisory, a vendor patch is reportedly in development.
Affected products
- schreibfaul1 ESP32-audioI2S 3.4.5
Timeline
- 2026-07-28: disclosed: CVE published to NVD