{
  "cveId": "CVE-2026-27205",
  "url": "https://patchblox.com/security/cve/CVE-2026-27205",
  "summary": "CVE-2026-27205 is fixed in 4 products on 1 platform, first by python3-flask 1.1.1-2ubuntu0.1\u002Besm1, released February 20, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "flask: Flask is a web server gateway interface (WSGI) web application framework",
  "description": "Flask is a web server gateway interface (WSGI) web application framework. In versions 3.1.2 and below, when the session object is accessed, Flask should set the Vary: Cookie header., resulting in a Use of Cache Containing Sensitive Information vulnerability. The logic instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked. The severity and risk depend on the application being hosted behind a caching proxy that doesn\u0027t ignore responses with cookies, not setting a Cache-Control header to mark pages as private or non-cacheable, and accessing the session in a way that only touches keys without reading values or mutating the session. The issue has been fixed in version 3.1.3.",
  "published": "2026-02-20T22:17:00Z",
  "severity": "medium",
  "cvss": 4.3,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N",
  "epss": 0.004,
  "epssPercentile": 0.34536,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "flask",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "3.1.1-1\u002Bdeb13u1",
      "fix": "DEBIAN-CVE-2026-27205",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-27205",
      "released": "2026-02-21T06:17:00Z"
    },
    {
      "platform": "linux",
      "product": "flask",
      "release": "Debian 14",
      "fixedVersion": "3.1.3-1",
      "fix": "DEBIAN-CVE-2026-27205",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-27205",
      "released": "2026-02-21T06:17:00Z"
    },
    {
      "platform": "linux",
      "product": "python-Flask",
      "release": "opensuse-leap 15.6",
      "fixedVersion": "2.3.2-150400.3.9.1",
      "fix": "SUSE-SU-2026:0849-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-0849-1",
      "released": "2026-03-09T10:13:40Z"
    },
    {
      "platform": "linux",
      "product": "python-Flask",
      "release": "sles 15.7",
      "fixedVersion": "2.3.2-150400.3.9.1",
      "fix": "SUSE-SU-2026:0849-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-0849-1",
      "released": "2026-03-09T10:13:40Z"
    },
    {
      "platform": "linux",
      "product": "python-Flask",
      "release": "sles 16.0",
      "fixedVersion": "3.1.1-160000.3.1",
      "fix": "SUSE-SU-2026:22023-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-22023-1",
      "released": "2026-06-02T17:26:47Z"
    },
    {
      "platform": "linux",
      "product": "python-flask-doc",
      "release": "amzn 2023",
      "fixedVersion": "1:1.1.4-5.amzn2023.0.1",
      "fix": "ALAS2023-2026-1476",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-1476",
      "released": "2026-03-16T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "python3-flask",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1.1.1-2ubuntu0.1\u002Besm1",
      "fix": "python3-flask 1.1.1-2ubuntu0.1\u002Besm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-python3-flask-1.1.1-2ubuntu0.1-esm1",
      "released": "2026-02-20T22:17:00Z"
    },
    {
      "platform": "linux",
      "product": "python3-flask",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "2.0.1-2ubuntu1.2",
      "fix": "python3-flask 2.0.1-2ubuntu1.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-python3-flask-2.0.1-2ubuntu1.2",
      "released": "2026-02-20T22:17:00Z"
    },
    {
      "platform": "linux",
      "product": "python3-flask",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "3.0.2-1ubuntu1.1",
      "fix": "python3-flask 3.0.2-1ubuntu1.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-python3-flask-3.0.2-1ubuntu1.1",
      "released": "2026-02-20T22:17:00Z"
    },
    {
      "platform": "linux",
      "product": "python3-flask",
      "release": "amzn 2023",
      "fixedVersion": "1:1.1.4-5.amzn2023.0.1",
      "fix": "ALAS2023-2026-1476",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-1476",
      "released": "2026-03-16T09:00:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}