ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to 3.11.1, the multipart/form-data parser in src/WebRequest.cpp stores _boundaryPosition as an 8-bit value while _parseMultipartPostByte processes the boundary. A remote request containing an exactly 256-byte multipart boundary wraps _boundaryPosition from 255 to zero, prevents the boundary parsing loop from terminating, consumes excessive CPU, and triggers a FreeRTOS watchdog reset on affected ESP32 or ESP8266 devices. This issue is fixed in version 3.11.1.
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Thu, 17 Sep 2026 18:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to 3.11.1, the multipart/form-data parser in src/WebRequest.cpp stores _boundaryPosition as an 8-bit value while _parseMultipartPostByte processes the boundary. A remote request containing an exactly 256-byte multipart boundary wraps _boundaryPosition from 255 to zero, prevents the boundary parsing loop from terminating, consumes excessive CPU, and triggers a FreeRTOS watchdog reset on affected ESP32 or ESP8266 devices. This issue is fixed in version 3.11.1. | |
| Title | ESPAsyncWebServer: Integer overflow in multipart boundary parser causes denial of service | |
| Weaknesses | CWE-190 | |
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cvssV4_0
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-09-17T18:28:26.977Z
Reserved: 2026-06-15T19:15:27.343Z
Link: CVE-2026-54571
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