Espressif arduino-esp32 up to 3.2.0 HTTP Header response splitting

Summaryinfo

A vulnerability marked as critical has been reported in Espressif arduino-esp32 up to 3.2.0. This affects an unknown function of the component HTTP Header Handler. The manipulation leads to response splitting. This vulnerability is listed as CVE-2025-53007. The attack may be initiated remotely. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Espressif arduino-esp32 up to 3.2.0. This issue affects an unknown code of the component HTTP Header Handler. The manipulation with an unknown input leads to a response splitting vulnerability. Using CWE to declare the problem leads to CWE-113. The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

arduino-esp32 provides an Arduino core for the ESP32. Versions prior to 3.3.0-RC1 and 3.2.1 contain a HTTP Response Splitting vulnerability. The `sendHeader` function takes arbitrary input for the HTTP header name and value, concatenates them into an HTTP header line, and appends this to the outgoing HTTP response headers. There is no validation or sanitization of the `name` or `value` parameters before they are included in the HTTP response. If an attacker can control the input to `sendHeader` (either directly or indirectly), they could inject carriage return (`\r`) or line feed (`\n`) characters into either the header name or value. This could allow the attacker to inject additional headers, manipulate the structure of the HTTP response, potentially inject an entire new HTTP response (HTTP Response Splitting), and/or ause header confusion or other HTTP protocol attacks. Versions 3.3.0-RC1 and 3.2.1 contain a fix for the issue.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2025-53007 since 06/24/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available.

It is declared as proof-of-concept.

Upgrading to version 3.2.1 or 3.3.0-RC1 eliminates this vulnerability. Applying the patch 21640ac82a1bb5efa8cf0b3841be1ac80add6785 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-19198). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• Espressif

Name

• arduino-esp32

Version

• 3.0
• 3.1
• 3.2.0

License

• open-source

Website

• Product: https://github.com/espressif/arduino-esp32/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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