OESA-2023-1515

werkzeug German noun: "tool". Etymology: werk ("work"), zeug ("stuff") Werkzeug is a comprehensive WSGI_ web application library. It began as a simple collection of various utilities for WSGI applications and has become one of the most advanced WSGI utility libraries. It includes:

• An interactive debugger that allows inspecting stack traces and source code in the browser with an interactive interpreter for any frame in the stack. - A full-featured request object with objects to interact with headers, query args, form data, files, and cookies. - A response object that can wrap other WSGI applications and handle streaming data. - A routing system for matching URLs to endpoints and generating URLs for endpoints, with an extensible system for capturing variables from URLs. - HTTP utilities to handle entity tags, cache control, dates, user agents, cookies, files, and more. - A threaded WSGI server for use while developing applications locally. - A test client for simulating HTTP requests during testing without requiring running a server. Werkzeug doesn't enforce any dependencies. It is up to the developer to choose a template engine, database adapter, and even how to handle requests. It can be used to build all sorts of end user applications such as blogs, wikis, or bulletin boards. Flask_ wraps Werkzeug, using it to handle the details of WSGI while providing more structure and patterns for defining powerful applications.

Security Fix(es):

Werkzeug is a comprehensive WSGI web application library. Browsers may allow "nameless" cookies that look like =value instead of key=value. A vulnerable browser may allow a compromised application on an adjacent subdomain to exploit this to set a cookie like =__Host-test=bad for another subdomain. Werkzeug prior to 2.2.3 will parse the cookie =__Host-test=bad as __Host-test=bad`. 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.(CVE-2023-23934)

Werkzeug is a comprehensive WSGI web application library. Prior to version 2.2.3, Werkzeug's multipart form data parser will parse an unlimited number of parts, including file parts. Parts can be a small amount of bytes, but each requires CPU time to parse and may use more memory as Python data. If a request can be made to an endpoint that accesses request.data, request.form, request.files, or request.get_data(parse_form_data=False), it can cause unexpectedly high resource usage. This allows an attacker to cause a denial of service by sending crafted multipart data to an endpoint that will parse it. The amount of CPU time required can block worker processes from handling legitimate requests. The amount of RAM required can trigger an out of memory kill of the process. Unlimited file parts can use up memory and file handles. If many concurrent requests are sent continuously, this can exhaust or kill all available workers. Version 2.2.3 contains a patch for this issue.(CVE-2023-25577)