CVE-2026-42855 Details
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.
A vulnerability exists in the Arduino core for ESP32 microcontrollers, specifically in versions prior to 3.3.8. The issue arises in the WebServer library's Digest authentication implementation, which incorrectly computes the authentication hash using the URI from the client's Authorization header without verifying its accuracy against the actual requested URI. This flaw enables an attacker with a valid digest response (from one URI) to authenticate requests to a different protected URI, effectively bypassing access controls. The vulnerability is rooted in a failure to adhere to RFC 7616, which mandates that the server verify the URI in the Authorization header before accepting the digest response.
Users can upgrade to Arduino-ESP32 version 3.3.8 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed May 13, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/espressif/arduino-esp32/security/advisories/GHSA-28hv-fwm3-rpcq | [email protected] | ExploitVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| NVD-CWE-noinfo | Insufficient Information to Classify Weakness | [email protected] |
| CWE-287 | Improper Authentication | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| espressif arduino-esp32 | < 3.3.8 |
CPE
Remediation
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Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 15, 2026 | Initial Analysis | [email protected] |
| May 12, 2026 | New CVE Received | [email protected] |