CVE-2026-28367 is a vulnerability identified in the Undertow web server component used within the Red Hat build of Apache Camel for Spring Boot 4. The flaw arises from inconsistent parsing of HTTP request header terminators, specifically when an attacker sends a sequence of carriage return characters (`\r\r\r`) as the header block terminator. This malformed input can be interpreted differently by the backend server and intermediate proxy servers, such as older versions of Apache Traffic Server and Google Cloud Classic Application Load Balancer. This discrepancy enables HTTP request smuggling attacks, where an attacker can desynchronize the front-end and back-end HTTP request parsing. Such desynchronization can allow attackers to bypass security controls, manipulate or inject unauthorized HTTP requests, and potentially gain unauthorized access to sensitive information or perform actions on behalf of legitimate users. The vulnerability does not require authentication or user interaction but has a high attack complexity due to the need to craft precise malformed requests and target specific proxy configurations. The CVSS 3.1 score of 8.7 reflects the high impact on confidentiality and integrity, while availability is not affected. No public exploits have been reported yet, but the vulnerability's presence in widely used middleware and proxy components makes it a significant risk. The lack of patch links suggests that remediation may require updates from Red Hat or configuration changes in proxy servers.

The primary impact of CVE-2026-28367 is the potential for attackers to perform HTTP request smuggling attacks, which can lead to unauthorized access to protected resources, session hijacking, web cache poisoning, and bypassing of security controls such as firewalls or authentication mechanisms. This can compromise the confidentiality and integrity of web applications relying on the affected Red Hat build of Apache Camel for Spring Boot 4 and associated proxy infrastructure. Organizations operating critical web services or APIs with these components may face data breaches, unauthorized transactions, or service manipulation. Although availability is not directly impacted, the indirect consequences of compromised integrity and confidentiality can disrupt business operations and damage reputation. The high attack complexity limits exploitation to skilled attackers with knowledge of the target environment, but the widespread use of Apache Camel and common proxy servers increases the attack surface. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits after public disclosure.

To mitigate CVE-2026-28367, organizations should: 1) Apply any available patches or updates from Red Hat for Apache Camel and Undertow components as soon as they are released. 2) Review and update proxy server software, particularly Apache Traffic Server and Google Cloud Classic Application Load Balancer, to versions that correctly handle HTTP header terminators and prevent request smuggling. 3) Implement strict input validation and normalization of HTTP headers at the edge and backend servers to detect and reject malformed requests containing unusual carriage return sequences. 4) Employ Web Application Firewalls (WAFs) with rules designed to detect and block HTTP request smuggling patterns. 5) Conduct thorough security testing, including fuzzing and penetration testing, focusing on HTTP request parsing and proxy behavior to identify potential desynchronization issues. 6) Monitor web server and proxy logs for anomalies indicative of request smuggling attempts, such as unexpected request sequences or header anomalies. 7) Consider architectural changes to reduce reliance on vulnerable proxy configurations or introduce additional layers of request validation. 8) Educate development and operations teams about HTTP request smuggling risks and secure coding practices related to HTTP header handling.