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HIGH · 7.5

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-esp3...

Vulnerability 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.

CVSS Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE

Affected Products

VendorProductVersions
EspressifArduino-Esp32< 3.3.8

Related Weaknesses (CWE)

CWE-287

References

FAQ

What is CVE-2026-42855?

CVE-2026-42855 is a vulnerability with a CVSS score of 7.5 (HIGH). 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-esp3...

How severe is CVE-2026-42855?

CVE-2026-42855 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-42855?

Check the references section above for vendor advisories and patch information. Affected products include: Espressif Arduino-Esp32.