CVE-2021-32715 : What You Need to Know

A detailed overview of CVE-2021-32715 focusing on the vulnerability found in hyper prior to version 0.14.10 due to lenient parsing of the Content-Length header when prefixed with a plus sign.

Understanding CVE-2021-32715

This section dives into what CVE-2021-32715 entails, its impact, technical details, and mitigation strategies.

What is CVE-2021-32715?

CVE-2021-32715 highlights a vulnerability in hyper, an HTTP library for Rust. The flaw lies in hyper's HTTP/1 server code, enabling incorrect parsing of requests with a prefixed plus sign in the

Content-Length

header.

The Impact of CVE-2021-32715

The vulnerability could lead to request smuggling or desync attacks, especially in versions of hyper prior to 0.14.10. Attackers could exploit this with an upstream HTTP proxy that forwards such headers.

Technical Details of CVE-2021-32715

This section delves into the specifics of the vulnerability, including its description, affected systems, and exploitation mechanisms.

Vulnerability Description

The flaw originates from the lenient parsing of the

Content-Length

header, allowing for the acceptance of illegitimate requests with a plus sign prefix.

Affected Systems and Versions

All hyper versions before 0.14.10 are impacted if compiled with

rustc

v1.5.0 or newer.

Exploitation Mechanism

Through upstream HTTP proxies that forward

Content-Length

headers with a plus sign prefix, attackers could conduct request smuggling or desync attacks.

Mitigation and Prevention

This section provides insights into immediate steps to take and long-term security practices to enhance mitigation strategies.

Immediate Steps to Take

Consider manually rejecting requests with a plus sign prefix in the

Content-Length

header or ensuring that upstream proxies handle such headers correctly.

Long-Term Security Practices

Adopt robust HTTP request handling mechanisms, perform regular security audits, and keep systems updated to prevent such vulnerabilities.

Patching and Updates

It is crucial to update to hyper version 0.14.10, where the vulnerability has been patched, to mitigate the risks effectively.