Vulnerability · Published May 12, 2026 · Assigned by GitHub_M
CVE-2026-42855arduino-esp32: Digest authentication URI mismatch bypass in WebServer allows cross-resource replay attack
High 7.5
In plain English
A high-severity improper authentication in arduino-esp32 from espressif. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| espressif | arduino-esp32 | < 3.3.8 |
Weakness: CWE-287 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N