CVE-2025-53007

arduino-esp32 vulnerable to CRLF injection in WebServer.cpp

Published Jun 26, 2025 CVSS 4.0 · 8.9 High EPSS < 1% KEV · Not listed

Description

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.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

espressif

arduino-esp32

affected

Version	Status	Constraints
`< 3.2.1`	affected	—
`>= 3.3.0-alpha1, < 3.3.0-RC1`	affected	—

No data.

No data available yet.

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
EUVD	EUVD-2025-19198	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.

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.470% probability within 30 days)

Exploitation none

Automatable yes

Technical Impact partial

References

Link	Providers
https://github.com/espressif/arduino-esp32/blob/9e61fa7e4bce59c05cb17c15b11b53b9bafca077/libraries/WebServer/src/WebServer.cpp#L504-L521
https://github.com/espressif/arduino-esp32/blob/9e61fa7e4bce59c05cb17c15b11b53b9bafca077/libraries/WebServer/src/WebServer.cpp#L577-L582
https://github.com/espressif/arduino-esp32/commit/21640ac82a1bb5efa8cf0b3841be1ac80add6785
https://github.com/espressif/arduino-esp32/security/advisories/GHSA-5476-9jjq-563m

History

Jun 27, 2025 4:15 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Jun 26, 2025 3:00 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		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.
Title		arduino-esp32 vulnerable to CRLF injection in WebServer.cpp
Weaknesses		CWE-113
References		https://github.com/espressif/arduino-esp32/blob/9e61fa7e4bce59c05cb17c15b11b53b9bafca077/libraries/WebServer/src/WebServer.cpp#L504-L521 https://github.com/espressif/arduino-esp32/blob/9e61fa7e4bce59c05cb17c15b11b53b9bafca077/libraries/WebServer/src/WebServer.cpp#L577-L582 https://github.com/espressif/arduino-esp32/commit/21640ac82a1bb5efa8cf0b3841be1ac80add6785 https://github.com/espressif/arduino-esp32/security/advisories/GHSA-5476-9jjq-563m
Metrics		cvssV4_0 `{'score': 8.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P'}`