CVE-2026-42855

High

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 Digest authentication implementation in arduino-esp32 computes the authentication hash using the URI field from the client's Authorization header, without verifying that it matches the actual requested URI. This allows an attacker who possesses any valid digest response (computed for URI-A) to authenticate requests to a completely different protected URI (URI-B), bypassing per-resource access control. This vulnerability is fixed in 3.3.8.

SeverityHigh
CVSS7.5
Exploit probability—
ProductEspressif Arduino-esp32
PublishedMay 12, 2026
First seenMay 12, 2026

How to fix

Update
  • espressif arduino-esp323.3.8 or later

Affected products

ProductAffected versionsFixed in
espressif arduino-esp32v < 3.3.83.3.8

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CVE-2026-42855 · Espressif Arduino-esp32 · Dark Radar