CVE-2023-30861

Aliases:GHSA-m2qf-hxjv-5gpqPYSEC-2023-62
Advisory lineage Upstream: 0 Downstream: 16
Modified
Published: 02 May 2023, 17:04
Last modified:13 Feb 2025, 16:49

Vulnerability Summary

Overall Risk (default)
medium
30/100
CVSS Score
7.5 HIGH
v3.1 (cve.org)
EPSS Score
0.22% LOW
0% probability +0.04%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

02 May 2023, 17:04
Published
Vulnerability first disclosed
13 Feb 2025, 16:49
Last Modified
Vulnerability information updated

Description

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 Metrics

  • v4.0•HIGH•Score: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
  • v3.1•HIGH•Score: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Trends

Current EPSS score: 0.22%• Percentile: 45%

Techniques & Countermeasures

  • CWE-539•Use of Persistent Cookies Containing Sensitive Information

    The web application uses persistent cookies, but the cookies contain sensitive information.

Affected Systems

  • pallets•flask

    ≥ 2.3.0, < 2.3.2 | < 2.2.5

  • palletsprojects•flask

    < 2.2.5 | ≥ 2.3.0, < 2.3.2

  • PyPI•flask

    < 2.2.5 | < afd63b16170b7c047f5758eb910c416511e9c965 | ≥ 2.3.0, < 2.3.2

References (12)