CVE-2026-42854
arduino-esp32: Stack buffer overflow in WebServer multipart boundary parsing leads to remote crash potential RCE
CVSS Score
9.8
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-121 |
| Vendor | espressif |
| Product | arduino-esp32 |
| Published | May 12, 2026 |
| Last Updated | May 13, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
espressif / arduino-esp32
< 3.3.8