CVE-2026-42854
9.8 · CRITICALOverview
CVE-2026-42854 is a critical-severity vulnerability affecting espressif arduino-esp32. It was published on May 12, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from espressif. Update arduino-esp32 to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| espressif | arduino-esp32 | >= 0, < 3.3.8 | Affected |
Frequently Asked Questions
What is CVE-2026-42854?
CVE-2026-42854 is a critical-severity vulnerability affecting espressif arduino-esp32. It was published on May 12, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
How severe is CVE-2026-42854?
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-42854?
Check the references section for vendor advisories and patches from espressif. Update arduino-esp32 to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-42854?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-42854 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
AI-driven PR review catches vulnerable dependencies before they ship.
Browser-based exploitation validates findings with real proof-of-concept.
Related CRITICAL CVEs from 2026
View all →A command injection vulnerability in the execute_command function of terminal-controller-mcp 0.1.7 a
n8n is an open source workflow automation platform. Versions starting with 1.65.0 and below 1.121.0
Fastjson before 1.2.48 mishandles autoType because, when an @type key is in a JSON document, and the
This vulnerability allows authenticated attackers to execute commands via the hostname of the device
Remote Code Execution vulnerability that allows unauthenticated attackers to inject arbitrary comman
XWiki Full Calendar Macro displays objects from the wiki on the calendar. Prior to version 2.4.5, us
Successful exploitation of the SQL injection vulnerability could allow an unauthenticated remote att
A static password reset token in the password reset function of DDSN Interactive Acora CMS v10.7.1 a
Affected devices do not properly enforce user authentication on specific API endpoints. This could f
Sandbox escape in the Messaging System component. This vulnerability was fixed in Firefox 147 and Th
OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or mor
Enclave is a secure JavaScript sandbox designed for safe AI agent code execution. Prior to 2.7.0, th