🛡️ CVE-2026-42854
🔴 CVSS 9.8 — Critical ⚠️ Exploit Public CWE-121 NVD
9.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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 header field (Content-Type: multipart/form-data; boundary=...) without enforcing any length limit. Sending a boundary string longer than ~8000 characters overflows the 8192-byte task stack of the loopTask, causing a crash and potential remote code execution. This vulnerability is fixed in 3.3.8.

Details

Severity CRITICAL
CVSS Score 9.8
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE CWE-121
Public Exploit ⚠️ Yes
Source NVD
Published 2026-05-12
Updated 2026-06-02
Modified 2026-05-18
Fix URL N/A

Affected Packages

Software From version Fixed in
arduino-esp32 — 3.3.8
unknown — —

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