Live › vulnerability › CVE-2026-62966
ESPAsyncWebServer is an HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350 boards. A malformed multipart file upload makes the parser write through a null pointer, which reboots an ESP32 and gives a remote attacker a denial of service.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-30 21:25 UTC. All times on this page are UTC.
Devices running ESPAsyncWebServer older than version 3.11.2 that expose a route with a non-trivial body or upload handler, such as a file-upload or web-OTA endpoint, are exposed. Projects without such a route, or that run a patched version, can skip it.
No product ranges from the sources yet.
ESPAsyncWebServer library version in the project's platformio.ini or library.json, or the Arduino library manager list.3.11.2Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
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.
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