Information Exposure Affecting flask package, versions [,2.2.5) [2.3.0,2.3.2)


Severity

0.0
high
0
10

    Threat Intelligence

    EPSS
    0.19% (57th percentile)

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  • Snyk ID SNYK-PYTHON-FLASK-5490129
  • published 2 May 2023
  • disclosed 1 May 2023
  • credit Tom Most

How to fix?

Upgrade flask to version 2.2.5, 2.3.2 or higher.

Overview

Affected versions of this package are vulnerable to Information Exposure in the form of exposing the permanent session cookie, when all of the following conditions are met:

  1. The application is 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 is 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.

A response containing data intended for one client may be cached and sent to other clients. If the proxy also caches Set-Cookie headers, it may send one client's session cookie to other clients. Under these conditions, the Vary: Cookie header is not set when a session is refreshed (re-sent to update the expiration) without being accessed or modified.

CVSS Scores

version 3.1
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Snyk

7.5 high
  • Attack Vector (AV)
    Network
  • Attack Complexity (AC)
    Low
  • Privileges Required (PR)
    None
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    High
  • Integrity (I)
    None
  • Availability (A)
    None
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NVD

7.5 high
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SUSE

7.5 high
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Red Hat

7.5 high