CVE-2019-16789 : Exploit Details and Defense Strategies
Learn about CVE-2019-16789, a vulnerability in Waitress versions prior to 1.4.0 that could lead to HTTP request smuggling. Find out the impact, affected systems, exploitation mechanism, and mitigation steps.
In versions of Waitress prior to 1.4.0, a security vulnerability allowed attackers to send crafted requests through a proxy server, potentially leading to HTTP request smuggling.
Understanding CVE-2019-16789
This CVE describes a vulnerability in Waitress that could result in HTTP request smuggling due to the mishandling of special whitespace characters in the Transfer-Encoding header.
What is CVE-2019-16789?
Waitress versions before 1.4.0 were susceptible to a security issue where specially crafted requests could be interpreted differently by Waitress when sent through a proxy server, potentially leading to HTTP request smuggling.
The Impact of CVE-2019-16789
The vulnerability could allow for HTTP request smuggling, potentially enabling cache poisoning or unintended information disclosure. This issue was resolved in Waitress version 1.4.1 through enhanced validation of HTTP fields.
Technical Details of CVE-2019-16789
This section provides more in-depth technical insights into the vulnerability.
Vulnerability Description
The vulnerability in Waitress stemmed from the incorrect parsing of requests containing special whitespace characters in the Transfer-Encoding header, leading to potential HTTP request smuggling.
Affected Systems and Versions
- Product: Waitress
- Vendor: Pylons
- Versions Affected: < 1.4.1
Exploitation Mechanism
Attackers could exploit this vulnerability by sending crafted requests through a proxy server, bypassing the front-end server's interpretation and potentially causing HTTP request smuggling.
Mitigation and Prevention
To address CVE-2019-16789 and enhance security, consider the following steps:
Immediate Steps to Take
- Enable additional protections on front-end servers to drop requests with a 400 Bad Request response.
- Waitress version 1.4.1 now responds correctly with a 400 Bad Request and drops connections to prevent potential HTTP pipelining issues.
Long-Term Security Practices
- Regularly update Waitress to the latest version to ensure security patches are applied.
- Implement strict HTTP field validation to prevent similar vulnerabilities.
Patching and Updates
- Update Waitress to version 1.4.1 or newer to mitigate the vulnerability and enhance security.