CVE-2023-30861 – flask

Package

Manager: pip
Name: flask
Vulnerable Version: >=2.3.0 <2.3.2 || >=0 <2.2.5

Severity

Level: High

CVSS v3.1: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

EPSS: 0.00213 pctl0.43869

Details

Flask vulnerable to possible disclosure of permanent session cookie due to missing Vary: Cookie header When all of the following conditions are met, a response containing data intended for one client may be cached and subsequently sent by a 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`](https://flask.palletsprojects.com/en/2.3.x/api/#flask.session.permanent). 2. The application does not access or modify the session at any point during a request. 4. [`SESSION_REFRESH_EACH_REQUEST`](https://flask.palletsprojects.com/en/2.3.x/config/#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. 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.

Metadata

Created: 2023-05-01T19:22:20Z
Modified: 2024-09-20T17:51:00Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2023/05/GHSA-m2qf-hxjv-5gpq/GHSA-m2qf-hxjv-5gpq.json
CWE IDs: ["CWE-539"]
Alternative ID: GHSA-m2qf-hxjv-5gpq
Finding: F042
Auto approve: 1