CVE-2026-23833

LOW EPSS 19.1%
Published Jan 19, 20265mo ago · Modified Jun 17, 20262w ago
1.7 CVSS 4.0
Low
Find Similar
Published Jan 19, 2026 5mo ago
Last Modified Jun 17, 2026 2w ago

Description

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 Details

Base Score
1.7
Exploitability
—
Impact
—
Vector string
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
19.1% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-190 Integer Overflow or Wraparound Numeric Error

Affected Products 1

VendorProductVersionRange
esphomeesphome*≥2025.9.0  –  <2025.12.7

References 4

  • esphome.io https://esphome.io/guides/security_best_practices
    Technical Description
  • github.com https://github.com/esphome/esphome/commit/69d7b6e9210390051318bd8e6410727689de08d6
    Patch
  • github.com https://github.com/esphome/esphome/pull/13306
    Issue TrackingPatch
  • github.com https://github.com/esphome/esphome/security/advisories/GHSA-4h3h-63v6-88qx
    MitigationPatchVendor Advisory

Remediation

  • github.com https://github.com/esphome/esphome/commit/69d7b6e9210390051318bd8e6410727689de08d6
    Patch
  • github.com https://github.com/esphome/esphome/pull/13306
    Issue TrackingPatch
  • github.com https://github.com/esphome/esphome/security/advisories/GHSA-4h3h-63v6-88qx
    MitigationPatchVendor Advisory