概要

Flask is a lightweight WSGI web application framework. When all of the following conditions are met, a response containing data intended for one client may be cached and subsequently sent by the proxy to other clients. If the proxy also caches `Set-Cookie` headers, it may send one client s `session` cookie to other clients. The severity depends on the application s use of the session and the proxy s behavior regarding cookies. The risk depends on all these conditions being met.1. The application must be hosted behind a caching proxy that does not strip cookies or ignore responses with cookies.2. The application sets `session.permanent = True`3. The application does not access or modify the session at any point during a request.4. `SESSION_REFRESH_EACH_REQUEST` enabled (the default).5. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.This happens because vulnerable versions of Flask only set the `Vary: Cookie` header when the session is accessed or modified, not when it is refreshed (re-sent to update the expiration) without being accessed or modified. This issue has been fixed in versions 2.3.2 and 2.2.5.

CVSS v3 指标

安全公告

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