{"id":"CVE-2026-42854","summary":"arduino-esp32: Stack buffer overflow in WebServer multipart boundary parsing leads to remote crash potential RCE","details":"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.","aliases":["GHSA-8cmm-3887-r32j"],"modified":"2026-08-12T03:51:18.234673240Z","published":"2026-05-12T21:56:33.437Z","database_specific":{"cwe_ids":["CWE-121"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42854.json","cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42854.json"},{"type":"ADVISORY","url":"https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42854"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/espressif/arduino-esp32","events":[{"introduced":"0"},{"fixed":"b4f85baa2d4a251eb435e0f78fcdda1fb193791f"}],"database_specific":{"source":["AFFECTED_FIELD","CPE_RANGE"],"cpe":"cpe:2.3:a:espressif:arduino-esp32:*:-:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"3.3.8"}]}}],"versions":["3.3.7","3.3.6","3.3.6-RC1","3.3.5","3.3.4","3.3.3","3.3.2","3.3.1","3.3.0","3.2.1","3.1.3","3.2.0","3.2.0-RC2","3.2.0-RC1","3.1.2","3.1.1","3.0.5","3.0.4","3.0.3","3.0.2","3.0.1","3.0.0","3.0.0-rc3","3.0.0-rc2","3.0.0-rc1","3.0.0-alpha3","3.0.0-alpha2","3.0.0-alpha1","2.0.6","2.0.5","2.0.4","2.0.3","2.0.3-RC1","2.0.2","2.0.1","2.0.0","2.0.0-rc2","2.0.0-rc1","2.0.0-alpha1","1.0.6","1.0.5","1.0.5-rc7","1.0.5-rc6","1.0.5-rc5","1.0.5-rc4","1.0.5-rc3","1.0.5-rc2","1.0.5-rc1","1.0.4","1.0.4-rc1","1.0.3","1.0.3-rc3","1.0.3-rc2","1.0.3-rc1","1.0.2","1.0.2-rc2","1.0.2-rc1","1.0.1","1.0.1-rc4","1.0.1-rc3","1.0.1-rc2","1.0.1-rc1","1.0.0","1.0.0-rc4","1.0.0-rc3","1.0.0-rc2","1.0.0-rc1","1.0.0-RC0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42854.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}