CVE-2025-53094

Description

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.

Weakness Type (CWE)

CWE-93 CWE-93

CWE-113 CWE-113

References

Other References

https://github.com/ESP32Async/ESPAsyncWebServer/blob/1095dfd1ecf1a903aede29854232af1b24f089b1/src/AsyncWebHeader.cpp#L6-L32 https://github.com/ESP32Async/ESPAsyncWebServer/pull/211 https://github.com/ESP32Async/ESPAsyncWebServer/security/advisories/GHSA-87j8-6f7g-h8wh

Frequently Asked Questions

What is CVE-2025-53094? +

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.

How do I check if I'm vulnerable to CVE-2025-53094? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-44217

sse-channel is an SSE-implementation which can be used to any node.js http request/response stream. Prior to 4.0.1, implementations that allow …

CVE-2026-43968

Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in ninenines cowlib allows SSE event splitting and injection via unvalidated field …

CVE-2024-51501

Refit is an automatic type-safe REST library for .NET Core, Xamarin and .NET The various header-related Refit attributes (Header, HeaderCollection …

CVE-2025-59419

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.128.Final and 4.2.7.Final, the SMTP codec in Netty …

CVE-2025-57804

h2 is a pure-Python implementation of a HTTP/2 protocol stack. Prior to version 4.3.0, an HTTP/2 request splitting vulnerability allows …

CVE-2026-43969

Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in ninenines cowlib allows HTTP request splitting and cookie smuggling via unvalidated …