# CVE-2026-51270: schreibfaul1 ESP32-audioI2S heap overflow in htmlToUTF8

Source: https://junglewise.ai/threats/cve-2026-51270-schreibfaul1-esp32-audioi2s-heap-overflow-in-htmltoutf8  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-28. Updated: 2026-07-28  
License: CC BY 4.0 with a link back

CVE-2026-51270 · Severity: info · Published 2026-07-28

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.

Technologies: [Schreibfaul1 ESP32-audioI2S](https://junglewise.ai/threats/technologies/esp32-audioi2s). Vendors: [Schreibfaul1](https://junglewise.ai/threats/vendors/schreibfaul1).

## Quick answers

**Is CVE-2026-51270 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-51270 being exploited in the wild.

**How severe is CVE-2026-51270?** Informational severity, published 28 July 2026.

**Which products and versions are affected?** Schreibfaul1 ESP32-audioI2S 3.4.5.

**Is there a fix for CVE-2026-51270?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-51270 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-51270?** Check whether you run Schreibfaul1 ESP32-audioI2S at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## 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

## References

- [https://github.com/programmervuln/cveadvisory-/blob/main/CVE-2026-51270](https://github.com/programmervuln/cveadvisory-/blob/main/CVE-2026-51270)
- [https://github.com/schreibfaul1/ESP32-audioI2S/blob/master/src/Audio.cpp](https://github.com/schreibfaul1/ESP32-audioI2S/blob/master/src/Audio.cpp)

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