CVE-2019-17632 in Jetty
Summary
by MITRE
In Eclipse Jetty versions 9.4.21.v20190926, 9.4.22.v20191022, and 9.4.23.v20191118, the generation of default unhandled Error response content (in text/html and text/json Content-Type) does not escape Exception messages in stacktraces included in error output.
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Analysis
by VulDB Data Team • 02/28/2024
The vulnerability identified as CVE-2019-17632 affects Eclipse Jetty web server versions 9.4.21 through 9.4.23, representing a critical security flaw in the server's error handling mechanism. This issue specifically manifests when Jetty generates default error responses for unhandled exceptions, particularly in scenarios where stack traces are included in the error output. The vulnerability stems from insufficient input sanitization and output encoding practices within the server's default error page generation logic, creating a potential vector for malicious exploitation.
The technical flaw resides in the improper escaping of exception messages and stack trace information that Jetty includes in its default error responses. When an unhandled exception occurs within a web application running on affected Jetty versions, the server automatically generates an error page containing diagnostic information including the full stack trace and exception details. However, the implementation fails to properly escape or sanitize these exception messages before rendering them in the HTML or JSON error responses. This lack of proper output encoding creates a scenario where malicious actors can inject arbitrary content into error pages, potentially leading to cross-site scripting attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates opportunities for more sophisticated attacks within web application environments. When error responses contain unsanitized stack trace information, attackers can potentially extract sensitive application details such as file paths, internal system structures, and application logic patterns. This information can be leveraged to craft more targeted attacks against the affected web applications. The vulnerability affects both text/html and text/json content types, indicating the flaw exists across multiple response formats commonly used in web applications and APIs.
Security professionals should note this vulnerability aligns with CWE-79, which specifically addresses Cross-Site Scripting (XSS) vulnerabilities, and represents a classic example of improper output escaping in web applications. The flaw demonstrates the critical importance of input validation and output encoding in web server implementations, particularly in error handling scenarios where diagnostic information is displayed to end users. Organizations using affected Jetty versions should prioritize immediate remediation through version upgrades to patched releases, as the vulnerability can be exploited without authentication and provides attackers with valuable information for subsequent attack phases.
Mitigation strategies should include immediate patching of affected Jetty installations to versions that properly escape exception messages in error responses. Additionally, organizations should implement comprehensive monitoring for error page generation and consider implementing web application firewalls to detect and block suspicious error response patterns. The vulnerability also highlights the need for robust security testing practices that include error handling scenarios, particularly in web server configurations where diagnostic information is exposed to end users. Security teams should conduct thorough assessments of their web application error handling mechanisms to ensure similar vulnerabilities do not exist in custom error pages or application code.
This vulnerability exemplifies the broader category of information disclosure flaws that can significantly impact security posture when combined with other attack vectors. The error response handling in web servers represents a critical component of security architecture that requires careful attention to output encoding and sanitization practices. Organizations should establish security guidelines for error handling that mandate proper escaping of all diagnostic information in error responses, particularly in production environments where exposure to end users is inevitable. The remediation process should include not only updating the core Jetty components but also reviewing and updating any custom error handling logic that might exhibit similar vulnerabilities through the ATT&CK framework's T1211 technique for Exfiltration Through Command and Control Channel.