CVE-2026-42854

Summary: The Arduino-ESP32 core is affected by a stack overflow in the WebServer multipart boundary parser. A boundary derived from the HTTP header (Content-Type: multipart/form-data; boundary=...) with length > ~8000 can overflow the 8192-byte loopTask stack, potentially enabling remote code ...

CVE-2026-42854

arduino-esp32 is an Arduino core for the ESP32, ESP32-S2, ESP32-S3, ESP32-C3, ESP32-C6 and ESP32-H2 microcontrollers. Prior to 3.3.8, the WebServer multipart form parser in arduino-esp32 allocates a Variable Length Array VLA on the stack whose size is derived from an attacker-controlled HTTP head...