CVE-2026-23833Medium▾ SunlitESPHome vulnerable to denial-of-service via out-of-bounds check bypass in the API component
▾ Sunlit zone — Low / medium · no exploitation signal
impact 27.5 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 8.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
Last analysed / modified upstream
0.3%
0.3% → 0.3%
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.
ESPHome 2025.9.0 through 2025.12.6
Low - Users following Security Best Practices with API encryption enabled are not affected without knowledge of the encryption key.
Denial-of-service. An attacker with network access to port 6053 can crash and reboot the device.
Thanks to @Mat931 for responsibly reporting this vulnerability.
esphome >= 2025.9.0, < 2025.12.7Upgrade to a patched release:
esphome 2025.12.7Connected by shared product, vendor, weakness, or advisory.
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