CVE-2023-23934 : Exploit Details and Defense Strategies

This CVE involves Werkzeug's incorrect parsing of nameless cookies which can lead to __Host- cookies bypass vulnerability.

Understanding CVE-2023-23934

This vulnerability occurs due to Werkzeug, a comprehensive WSGI web application library, improperly parsing nameless cookies which can be exploited by compromised applications on adjacent subdomains.

What is CVE-2023-23934?

Werkzeug, prior to version 2.2.3, allows browsers to accept nameless cookies in the format

=value

instead of the standard

key=value

. This vulnerability can be exploited by malicious subdomains to set a cookie like

=__Host-test=bad

for another subdomain, bypassing security measures.

The Impact of CVE-2023-23934

An attacker can exploit this vulnerability to set malicious cookies on adjacent subdomains, potentially leading to unauthorized access, data manipulation, or session hijacking within affected applications running Werkzeug versions prior to 2.2.3.

Technical Details of CVE-2023-23934

The vulnerability is classified under CWE-20 (Improper Input Validation) and has a CVSSv3.1 base score of 2.6 (Low severity). It has a high attack complexity, requires user interaction, and an adjacent network vector.

Vulnerability Description

Werkzeug incorrectly parses nameless cookies, allowing malicious cookies to be set on adjacent subdomains bypassing security mechanisms.

Affected Systems and Versions

The vulnerability affects Werkzeug versions earlier than 2.2.3.

Exploitation Mechanism

By setting a nameless cookie in the form

=value

using a vulnerable browser, an attacker on an adjacent subdomain can exploit the vulnerability to bypass security measures and set malicious cookies.

Mitigation and Prevention

To mitigate the CVE-2023-23934 vulnerability, immediate steps must be taken along with long-term security practices and applying necessary patches and updates.

Immediate Steps to Take

Upgrade Werkzeug to version 2.2.3 or newer to address the vulnerability.
Avoid using vulnerable browsers that accept nameless cookies.

Long-Term Security Practices

Regularly update and patch software to prevent security vulnerabilities.
Implement proper input validation and security measures in web applications to mitigate similar risks.

Patching and Updates

Ensure prompt installation of security updates released by software vendors to address known vulnerabilities and enhance overall system security.