{"cve":"CVE-2026-23833","nvd":{"published":"2026-01-19T18:16:06.007","modified":"2026-06-17T10:22:10.463","status":"Analyzed","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_v4":{"vector":"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","score":1.7},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-190"],"references":["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"],"products":["esphome:esphome"],"source":"nvd","synced_at":"2026-10-19T22:21:16.563232421+00:00"},"epss":{"cve":"CVE-2026-23833","score":0.00301,"percentile":0.22877,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-4h3h-63v6-88qx","url":"https://osv.dev/vulnerability/GHSA-4h3h-63v6-88qx","summary":"ESPHome vulnerable to denial-of-service via out-of-bounds check bypass in the API component","modified":"2026-07-07T17:56:35.058004084Z","packages":[{"ecosystem":"PyPI","name":"esphome","purl":"pkg:pypi/esphome","ranges":[">=2025.9.0 <2025.12.7"],"fixed":["2025.12.7"]}]},{"id":"PYSEC-2026-1326","url":"https://osv.dev/vulnerability/PYSEC-2026-1326","summary":"ESPHome vulnerable to denial-of-service via out-of-bounds check bypass in the API component","modified":"2026-07-07T17:46:44.629274708Z","packages":[{"ecosystem":"PyPI","name":"esphome","purl":"pkg:pypi/esphome","ranges":[">=2025.9.0 <2025.12.7"],"fixed":["2025.12.7"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}