What is CVE-2026-42855?

CVE-2026-42855 is a high-severity vulnerability in Espressif Arduino-esp32, classified under Improper Authentication. CVSS score: 7.5/10. Published 2026-05-12.

How severe is CVE-2026-42855?

High severity. CVSS v3 base score is 7.5 out of 10.

Auth bypass in Espressif Arduino-esp32

CVE-2026-42855

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 Digest authentication implementation in arduino-esp32 computes the authentication hash usin…

Vulnerability class: Broken Authentication

EPSS: 0.000 (15.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

Affected products

Espressif Arduino-esp32 — versions < 3.3.8

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)

Frequently asked questions

What is CVE-2026-42855?: CVE-2026-42855 is a high-severity vulnerability in Espressif Arduino-esp32, classified under Improper Authentication. CVSS score: 7.5/10. Published 2026-05-12.
How severe is CVE-2026-42855?: High severity. CVSS v3 base score is 7.5 out of 10.