CVE-2025-53094: ESP32ASYNC Espasyncwebserver

High severity, CVSS 8.7. EPSS: 0.4% chance of exploitation in the next 30 days.

ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. In versions up to and including 3.7.8, a CRLF (Carriage Return Line Feed) injection vulnerability exists in the construction and output of HTTP headers within `AsyncWebHeader.cpp`. Unsanitized input allows attackers to inject CR (`\r`) or LF (`\n`) characters into header names or values, leading to arbitrary header or response manipulation. Manipulation of HTTP headers and responses can enable a wide range of attacks, making the severity of this vulnerability high. A fix is available at pull request 211 and is expected to be part of version 3.7.9.

Affected products

• ESP32ASYNC Espasyncwebserver: up to and including 3.7.8

Published 2025-06-27. Last modified 2026-06-17.