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CVE-2023-30861

CVE-2023-30861 · Flask vulnerable to possible disclosure of permanent session cookie due to missing Vary: Cookie header

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 7.5 · High · EPSS 1.2% · Public exploit · Fix available

Published
Updated

Stack: system · python

Affected products and versions

  • flask

    Versions
    • >= 2.3.0, < 2.3.2: Affected
    • < 2.2.5: Affected

    No fix published

  • flask Debian:12

    Affected ranges
    • ECOSYSTEM: < 2.2.2-3

    Update to 2.2.2-3

  • flask Debian:13

    Affected ranges
    • ECOSYSTEM: < 2.2.2-3

    Update to 2.2.2-3

  • flask Debian:14

    Affected ranges
    • ECOSYSTEM: < 2.2.2-3

    Update to 2.2.2-3

  • flask PyPI

    Versions
    • 2.3.0
    • 2.3.1
    Affected ranges
    • ECOSYSTEM: ≥ 2.3.0, < 2.3.2

    Update to 2.3.2

  • flask PyPI

    Versions
    • 0.1
    • 0.10
    • 0.10.1
    • 0.11
    • 0.11.1
    • 0.12
    • 0.12.1
    • 0.12.2
    • 0.12.3
    • 0.12.4
    • 0.12.5
    • 0.2
    • 0.3
    • 0.3.1
    • 0.4
    • 0.5
    • 0.5.1
    • 0.5.2
    • 0.6
    • 0.6.1
    • 0.7
    • 0.7.1
    • 0.7.2
    • 0.8
    • 0.8.1
    • 0.9
    • 1.0
    • 1.0.1
    • 1.0.2
    • 1.0.3
    • 1.0.4
    • 1.1.0
    • 1.1.1
    • 1.1.2
    • 1.1.3
    • 1.1.4
    • 2.0.0
    • 2.0.0rc1
    • 2.0.0rc2
    • 2.0.1
    • 2.0.2
    • 2.0.3
    • 2.1.0
    • 2.1.1
    • 2.1.2
    • 2.1.3
    • 2.2.0
    • 2.2.1
    • 2.2.2
    • 2.2.3
    • 2.2.4
    Affected ranges
    • ECOSYSTEM: < 2.2.5

    Update to 2.2.5

  • flask PyPI

    Versions
    • 0.1
    • 0.10
    • 0.10.1
    • 0.11
    • 0.11.1
    • 0.12
    • 0.12.1
    • 0.12.2
    • 0.12.3
    • 0.12.4
    • 0.12.5
    • 0.2
    • 0.3
    • 0.3.1
    • 0.4
    • 0.5
    • 0.5.1
    • 0.5.2
    • 0.6
    • 0.6.1
    • 0.7
    • 0.7.1
    • 0.7.2
    • 0.8
    • 0.8.1
    • 0.9
    • 1.0
    • 1.0.1
    • 1.0.2
    • 1.0.3
    • 1.0.4
    • 1.1.0
    • 1.1.1
    • 1.1.2
    • 1.1.3
    • 1.1.4
    • 2.0.0
    • 2.0.0rc1
    • 2.0.0rc2
    • 2.0.1
    • 2.0.2
    • 2.0.3
    • 2.1.0
    • 2.1.1
    • 2.1.2
    • 2.1.3
    • 2.2.0
    • 2.2.1
    • 2.2.2
    • 2.2.3
    • 2.2.4
    • 2.3.0
    • 2.3.1
    Affected ranges
    • {"events": [{"introduced": "0"}, {"fixed": "70f906c51ce49c485f1d355703e9cc3386b1cc2b"}, {"fixed": "afd63b16170b7c047f5758eb910c416511e9c965"}], "repo": "https://github.com/pallets/flask", "type": "GIT"}
    • ECOSYSTEM: < 2.2.5 ∪ ≥ 2.3.0, < 2.3.2

    Update to 2.2.5; Update to 2.3.2

  • flask Ubuntu:20.04:LTS

    Versions
    • 1.0.2-3
    • 1.1.1-2
    Affected ranges
    • ECOSYSTEM: < 1.1.1-2ubuntu0.1

    Update to 1.1.1-2ubuntu0.1

  • flask Ubuntu:22.04:LTS

    Versions
    • 1.1.2-2
    • 2.0.1-2ubuntu1
    Affected ranges
    • ECOSYSTEM: < 2.0.1-2ubuntu1.1

    Update to 2.0.1-2ubuntu1.1

Original sources

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