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.
                
            References
                    Configurations
                    Configuration 1 (hide)
            
            
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History
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Information
                Published : 2023-05-02 18:15
Updated : 2023-08-20 21:15
NVD link : CVE-2023-30861
Mitre link : CVE-2023-30861
CVE.ORG link : CVE-2023-30861
JSON object : View
Products Affected
                palletsprojects
- flask
 
CWE
                
                    
                        
                        CWE-539
                        
            Use of Persistent Cookies Containing Sensitive Information
