espressif arduino-esp32 up to 3.3.7 Authorization Header improper authentication

Summaryinfo

A vulnerability has been found in espressif arduino-esp32 up to 3.3.7 and classified as critical. This vulnerability affects unknown code of the component Authorization Header Handler. The manipulation leads to improper authentication. This vulnerability is listed as CVE-2026-42855. The attack may be initiated remotely. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in espressif arduino-esp32 up to 3.3.7 and classified as critical. This issue affects an unknown part of the component Authorization Header Handler. The manipulation with an unknown input leads to a improper authentication vulnerability. Using CWE to declare the problem leads to CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Impacted is confidentiality. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-42855 since 04/30/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 3.3.8 eliminates this vulnerability.

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Productinfo

Vendor

• espressif

Name

• arduino-esp32

Version

• 3.3.0
• 3.3.1
• 3.3.2
• 3.3.3
• 3.3.4
• 3.3.5
• 3.3.6
• 3.3.7

Website

• Product: https://github.com/espressif/arduino-esp32/

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