---
cve: "CVE-2026-42854"
severity: "CRITICAL"
cvss: 9.8
epss: "0.8%"
vendor: "espressif"
kev: false
exploited: false
published: "2026-05-12 22:16:34"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-10-02T22:21:57+02:00"
---

# CVE-2026-42854

> 9.8 CRITICAL · 🧪 PoC

## Beschreibung

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.

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **poc**
  - Automatable: **yes**
  - Technical Impact: **total**

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- b4f85baa2d4a251eb435e0f78fcdda1fb193791f (Commit)

## Referenzen

- <https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-42854) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_