{"id":"CVE-2026-62966","state":"PUBLISHED","title":"ESPAsyncWebServer multipart parser has null-pointer write","description":"ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to version 3.11.2, the multipart parser in `src/WebRequest.cpp` frees `_itemBuffer` and sets it to NULL when `BOUNDARY_OR_DATA` matches the closing boundary of a file part, before confirming the following terminator, while leaving `_itemIsFile` true. If the next byte is neither the final closing dashes nor a clean CRLF, the `DASH3_OR_RETURN2` or `EXPECT_FEED2` rewind branch re-injects provisionally consumed bytes through `itemWriteByte`. Because `_itemIsFile` remains true, `_itemBuffer`[`_itemBufferIndex`++] writes through a null pointer. On ESP32 this causes a `StoreProhibited` exception, panic and device reboot, producing remote denial of service. A route with a non-trivial body/upload handler, such as a file-upload or web-OTA endpoint, must be present. This issue is fixed in version 3.11.2.","publishedAt":"2026-10-30T20:53:37.292Z","updatedAt":"2026-10-30T20:53:37.292Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["ESP32Async ESPAsyncWebServer"],"affected":[{"vendor":"ESP32Async","product":"ESPAsyncWebServer","versions":[{"version":"< 3.11.2","status":"affected"}]}],"references":["https://github.com/ESP32Async/ESPAsyncWebServer/security/advisories/GHSA-8m8p-vhxc-jmjw","https://github.com/ESP32Async/ESPAsyncWebServer/commit/4efbd35e597d91f01749f2d4a14bb78fba8ea02e","https://github.com/ESP32Async/ESPAsyncWebServer/tree/v3.11.2"],"weaknesses":["CWE-476","CWE-672"],"ingestedAt":"2026-10-30T20:56:06.379Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/62xxx/CVE-2026-62966.json","commit":"096fe98e99ae7a3dd439701185a44f9c91b425dc","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-62966","state":"PUBLISHED","datePublished":"2026-10-30T20:53:37.292Z","dateUpdated":"2026-10-30T20:53:37.292Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-14T22:48:09.779Z"},"containers":{"cna":{"title":"ESPAsyncWebServer multipart parser has null-pointer write","descriptions":[{"lang":"en","value":"ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to version 3.11.2, the multipart parser in `src/WebRequest.cpp` frees `_itemBuffer` and sets it to NULL when `BOUNDARY_OR_DATA` matches the closing boundary of a file part, before confirming the following terminator, while leaving `_itemIsFile` true. If the next byte is neither the final closing dashes nor a clean CRLF, the `DASH3_OR_RETURN2` or `EXPECT_FEED2` rewind branch re-injects provisionally consumed bytes through `itemWriteByte`. Because `_itemIsFile` remains true, `_itemBuffer`[`_itemBufferIndex`++] writes through a null pointer. On ESP32 this causes a `StoreProhibited` exception, panic and device reboot, producing remote denial of service. A route with a non-trivial body/upload handler, such as a file-upload or web-OTA endpoint, must be present. This issue is fixed in version 3.11.2."}],"affected":[{"vendor":"ESP32Async","product":"ESPAsyncWebServer","versions":[{"version":"< 3.11.2","status":"affected"}]}],"references":[{"url":"https://github.com/ESP32Async/ESPAsyncWebServer/security/advisories/GHSA-8m8p-vhxc-jmjw","name":"https://github.com/ESP32Async/ESPAsyncWebServer/security/advisories/GHSA-8m8p-vhxc-jmjw","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/ESP32Async/ESPAsyncWebServer/commit/4efbd35e597d91f01749f2d4a14bb78fba8ea02e","name":"https://github.com/ESP32Async/ESPAsyncWebServer/commit/4efbd35e597d91f01749f2d4a14bb78fba8ea02e","tags":["x_refsource_MISC"]},{"url":"https://github.com/ESP32Async/ESPAsyncWebServer/tree/v3.11.2","name":"https://github.com/ESP32Async/ESPAsyncWebServer/tree/v3.11.2","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-476","lang":"en","description":"CWE-476: NULL Pointer Dereference","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-672","lang":"en","description":"CWE-672: Operation on a Resource after Expiration or Release","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-30T20:53:37.292Z"},"source":{"advisory":"GHSA-8m8p-vhxc-jmjw","discovery":"UNKNOWN"}}}}}