CVE-2026-42855

Status: AnalyzedHigh (7.5)—

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

Version: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Base score: 7.5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.51%
Percentile among all scored CVEs: 41
Score date: 10/6/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1190 Exploit Public-Facing Applicationinitial access95 %
Primary impactT1078 Valid Accountsstealth · persistence · privilege escalation · initial access90 %
Secondary impactT1005 Data from Local Systemcollection75 %

Vulnerabilidad de autenticación en servidor web remoto (AV:N, PR:N, UI:N). Permite reutilizar credenciales digest válidas para acceder a recursos protegidos sin autorización (CWE-287, acceso no autorizado), y leer datos confidenciales (C:H).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Privileged Account Management Application Developer Guidance Active Directory Configuration Vulnerability Scanning User Training User Account Management

Affected technologies (1)

Espressif — Arduino-esp32

CWEs

CWE-287
NVD-CWE-noinfo

References

https://github.com/espressif/arduino-esp32/security/advisories/GHSA-28hv-fwm3-rpcq

Raw JSON (NVD)

Show

{
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          "version": "2.0.3",
          "timestamp": "2026-05-13T15:32:50.254940Z"
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          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 3.6,
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  "published": "2026-05-12T22:16:35.067",
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    }
  ],
  "lastModified": "2026-06-17T10:48:30.867",
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