CVE-2021-21299 : Exploit Details and Defense Strategies

A detailed overview of CVE-2021-21299, a vulnerability in the hyper open-source HTTP library for Rust that can lead to request smuggling attacks.

Understanding CVE-2021-21299

In this section, we will delve into the vulnerability, its impact, technical details, and mitigation strategies.

What is CVE-2021-21299?

CVE-2021-21299 affects the hyper HTTP library for Rust, versions prior to 0.13.10 and 0.14.3, allowing request smuggling attacks due to misinterpretation of multiple transfer-encoding headers.

The Impact of CVE-2021-21299

The vulnerability can be used for desync attacks, potentially enabling attackers to manipulate request payloads, leading to security compromises.

Technical Details of CVE-2021-21299

Let's explore the technical aspects of the vulnerability in this section.

Vulnerability Description

The flaw in the HTTP server code of hyper allows certain requests with multiple transfer-encoding headers to bypass validation, potentially resulting in request smuggling attacks.

Affected Systems and Versions

Versions of hyper before 0.13.10 and 0.14.3 are impacted by this vulnerability, making them susceptible to request smuggling attacks.

Exploitation Mechanism

Attackers can craft malicious requests with multiple transfer-encoding headers to exploit the misinterpretation in the hyper server, allowing for request smuggling.

Mitigation and Prevention

Discover how to prevent and mitigate the risks associated with CVE-2021-21299 in this section.

Immediate Steps to Take

To mitigate the vulnerability, consider rejecting requests containing a

transfer-encoding

header and ensure that upstream proxies handle

transfer-encoding

correctly.

Long-Term Security Practices

Implement strict header validation practices, regularly update libraries to patched versions, and monitor for any unusual request patterns to enhance overall security posture.

Patching and Updates

Ensure that all instances of hyper are updated to versions 0.13.10 or 0.14.3 to remediate the vulnerability and prevent potential request smuggling attacks.