{"id":"CVE-2026-42854","state":"PUBLISHED","title":"arduino-esp32: Stack buffer overflow in WebServer multipart boundary parsing leads to remote crash potential RCE","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 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.","publishedAt":"2026-05-12T21:56:33.437Z","updatedAt":"2026-05-13T14:24:52.597Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["espressif arduino-esp32"],"affected":[{"vendor":"espressif","product":"arduino-esp32","versions":[{"version":"< 3.3.8","status":"affected"}]}],"references":["https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j"],"weaknesses":["CWE-121"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/42xxx/CVE-2026-42854.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-42854","state":"PUBLISHED","datePublished":"2026-05-12T21:56:33.437Z","dateUpdated":"2026-05-13T14:24:52.597Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-04-30T16:44:48.378Z"},"containers":{"cna":{"title":"arduino-esp32: Stack buffer overflow in WebServer multipart boundary parsing leads to remote crash potential RCE","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."}],"affected":[{"vendor":"espressif","product":"arduino-esp32","versions":[{"version":"< 3.3.8","status":"affected"}]}],"references":[{"url":"https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j","name":"https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":9.8,"baseSeverity":"CRITICAL","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-121","lang":"en","description":"CWE-121: Stack-based Buffer Overflow","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-05-12T21:56:33.437Z"},"source":{"advisory":"GHSA-8cmm-3887-r32j","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/espressif/arduino-esp32/security/advisories/GHSA-8cmm-3887-r32j","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-13T14:24:33.796662Z","id":"CVE-2026-42854","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-13T14:24:52.597Z"}}]}}}