CVE-2019-9740 : What You Need to Know

A vulnerability was found in urllib2 in Python versions 2.x through 2.7.16 and urllib in Python versions 3.x through 3.7.3, allowing for CRLF injection if the attacker controls a URL parameter.

Understanding CVE-2019-9740

This CVE involves a security issue in Python versions that could lead to CRLF injection under certain conditions.

What is CVE-2019-9740?

CVE-2019-9740 is a vulnerability in Python's urllib2 and urllib modules that enables CRLF injection when an attacker can manipulate a URL parameter.

The Impact of CVE-2019-9740

The vulnerability allows attackers to insert malicious sequences into the query string, potentially leading to HTTP header injection or execution of Redis commands.

Technical Details of CVE-2019-9740

This section provides more in-depth technical insights into the CVE.

Vulnerability Description

The issue in urllib2 in Python 2.x through 2.7.16 and urllib in Python 3.x through 3.7.3 allows for CRLF injection by manipulating a URL parameter.

Affected Systems and Versions

Python 2.x through 2.7.16
Python 3.x through 3.7.3

Exploitation Mechanism

Attackers can exploit this vulnerability by inserting the \r\n sequence in the query string after a ? character, followed by an HTTP header or a Redis command.

Mitigation and Prevention

Protecting systems from CVE-2019-9740 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update Python to the fixed versions: v2.7.17, v2.7.18, v3.5.10, v3.6.12, v3.7.9, etc.
Monitor and restrict user input that may affect URL parameters.

Long-Term Security Practices

Implement input validation mechanisms to prevent malicious input.
Regularly update Python and other software components to patch vulnerabilities.

Patching and Updates

Ensure timely installation of security patches and updates to mitigate the risk of CRLF injection vulnerabilities.