CVE-2026-42854

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 multipart form parser in arduino-esp32 allocates a Variable Length Array (VLA) on the stack whose size is derived from an attacker-controlled HTTP header field (Content-Type: multipart/form-data; boundary=...) without enforcing any length limit. Sending a boundary string longer than ~8000 characters overflows the 8192-byte task stack of the loopTask, causing a crash and potential remote code execution. This vulnerability is fixed in 3.3.8.

CVSS v3 9.8 CRITICAL

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j	Exploit Vendor Advisory
https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:espressif:arduino-esp32:*:-:*:*:*:*:*:*

History

No history.

Information

Published : 2026-05-12 22:16

Updated : 2026-06-17 10:48

NVD link : CVE-2026-42854

Mitre link : CVE-2026-42854

CVE.ORG link : CVE-2026-42854

JSON object : View

Products Affected

espressif

arduino-esp32

CWE

CWE-121

Stack-based Buffer Overflow

{"id": "CVE-2026-42854", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-42854", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-05-13T14:24:33.796662Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.8, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 3.9}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "espressif", "product": "arduino-esp32", "versions": [{"status": "affected", "version": "< 3.3.8"}]}]}], "published": "2026-05-12T22:16:34.930", "references": [{"url": "https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j", "tags": ["Exploit", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j", "tags": ["Exploit", "Vendor Advisory"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-121"}]}], "descriptions": [{"lang": "en", "value": "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 multipart form parser in arduino-esp32 allocates a Variable Length Array (VLA) on the stack whose size is derived from an attacker-controlled HTTP header field (Content-Type: multipart/form-data; boundary=...) without enforcing any length limit. Sending a boundary string longer than ~8000 characters overflows the 8192-byte task stack of the loopTask, causing a crash and potential remote code execution. This vulnerability is fixed in 3.3.8."}], "lastModified": "2026-06-17T10:48:30.760", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:espressif:arduino-esp32:*:-:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "308785AC-A885-47B5-9131-64AE662B6525", "versionEndExcluding": "3.3.8"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}