CVE-2026-23833

ESPHome is a system to control microcontrollers remotely through Home Automation systems. In versions 2025.9.0 through 2025.12.6, an integer overflow in the API component's protobuf decoder allows denial-of-service attacks when API encryption is not used. The bounds check `ptr + field_length > end` in `components/api/proto.cpp` can overflow when a malicious client sends a large `field_length` value. This affects all ESPHome device platforms (ESP32, ESP8266, RP2040, LibreTiny). The overflow bypasses the out-of-bounds check, causing the device to read invalid memory and crash. When using the plaintext API protocol, this attack can be performed without authentication. When noise encryption is enabled, knowledge of the encryption key is required. Users should upgrade to ESPHome 2025.12.7 or later to receive a patch, enable API encryption with a unique key per device, and follow the Security Best Practices.

CVSS

No CVSS.

References

Link	Resource
https://esphome.io/guides/security_best_practices
https://github.com/esphome/esphome/commit/69d7b6e9210390051318bd8e6410727689de08d6
https://github.com/esphome/esphome/pull/13306
https://github.com/esphome/esphome/security/advisories/GHSA-4h3h-63v6-88qx

Configurations

No configuration.

History

19 Jan 2026, 18:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-01-19 18:16

Updated : 2026-01-26 15:05

NVD link : CVE-2026-23833

Mitre link : CVE-2026-23833

CVE.ORG link : CVE-2026-23833

JSON object : View

Products Affected

No product.

CWE

CWE-190

Integer Overflow or Wraparound

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