Werkzeug WSGI Vulnerability - CVE-2023-23934

Werkzeug is a comprehensive WSGI web application library. Browsers may allow quotnamelessquot cookies that look like value instead of keyvalue. A vulnerable browser may allow a compromised application on an adjacent subdomain to exploit this to set a cookie like __Host-testbad for another subdomain. Werkzeug prior to 2.2.3 will parse the cookie __Host-testbad as __Host-testbad. If a Werkzeug application is running next to a vulnerable or malicious subdomain which sets such a cookie using a vulnerable browser the Werkzeug application will see the bad cookie value but the valid cookie key. The issue is fixed in Werkzeug 2.2.3.