{
  "cveId": "CVE-2023-30861",
  "url": "https://patchblox.com/security/cve/CVE-2023-30861",
  "summary": "CVE-2023-30861 is fixed in 3 products on 1 platform, first by python3-flask 1.1.1-2ubuntu0.1, released May 2, 2023. It is not reported as exploited. Patch Radar priority: High.",
  "title": "flask: Flask is a lightweight WSGI web application framework",
  "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 \u0060Set-Cookie\u0060 headers, it may send one client\u0027s \u0060session\u0060 cookie to other clients. The severity depends on the application\u0027s use of the session and the proxy\u0027s 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 \u0060session.permanent = True\u0060 3. The application does not access or modify the session at any point during a request. 4. \u0060SESSION_REFRESH_EACH_REQUEST\u0060 enabled (the default). 5. The application does not set a \u0060Cache-Control\u0060 header to indicate that a page is private or should not be cached.  This happens because vulnerable versions of Flask only set the \u0060Vary: Cookie\u0060 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.",
  "published": "2023-05-02T11:15:00Z",
  "severity": "high",
  "cvss": 7.5,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
  "epss": 0.0125,
  "epssPercentile": 0.69602,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "flask",
      "release": "Debian 11.6 (bullseye)",
      "fixedVersion": "1.1.2-2\u002Bdeb11u1",
      "fix": "DSA-5442-1",
      "url": "https://patchblox.com/security/fix/linux/dsa-5442-1",
      "released": "2023-06-29T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "flask",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "2.2.2-3",
      "fix": "DEBIAN-CVE-2023-30861",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-30861",
      "released": "2023-05-02T18:15:52Z"
    },
    {
      "platform": "linux",
      "product": "flask",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "2.2.2-3",
      "fix": "DEBIAN-CVE-2023-30861",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-30861",
      "released": "2023-05-02T18:15:52Z"
    },
    {
      "platform": "linux",
      "product": "flask",
      "release": "Debian 14",
      "fixedVersion": "2.2.2-3",
      "fix": "DEBIAN-CVE-2023-30861",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-30861",
      "released": "2023-05-02T18:15:52Z"
    },
    {
      "platform": "linux",
      "product": "python-flask-doc",
      "release": "amzn 2023",
      "fixedVersion": "1:1.1.2-5.amzn2023.0.3",
      "fix": "ALAS2023-2023-183",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2023-183",
      "released": "2023-05-25T17:41:00Z"
    },
    {
      "platform": "linux",
      "product": "python3-flask",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1.1.1-2ubuntu0.1",
      "fix": "python3-flask 1.1.1-2ubuntu0.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-python3-flask-1.1.1-2ubuntu0.1",
      "released": "2023-05-02T11:15:00Z"
    },
    {
      "platform": "linux",
      "product": "python3-flask",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "2.0.1-2ubuntu1.1",
      "fix": "python3-flask 2.0.1-2ubuntu1.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-python3-flask-2.0.1-2ubuntu1.1",
      "released": "2023-05-02T11:15:00Z"
    },
    {
      "platform": "linux",
      "product": "python3-flask",
      "release": "amzn 2023",
      "fixedVersion": "1:1.1.2-5.amzn2023.0.3",
      "fix": "ALAS2023-2023-183",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2023-183",
      "released": "2023-05-25T17:41:00Z"
    },
    {
      "platform": "linux",
      "product": "python3-flask",
      "release": "ol 8",
      "fixedVersion": "1:0.12.2-4.0.1.el8",
      "fix": "ELSA-2023-12710",
      "url": "https://patchblox.com/security/fix/linux/elsa-2023-12710",
      "released": "2023-08-06T00:00:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T19:38:12Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}