CVE-2023-30861: Flask Cookie Header Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-m2qf-hxjv-5gpq",
  "modified" : "2024-09-20T17:51:00Z",
  "published" : "2023-05-01T19:22:20Z",
  "aliases" : [ "CVE-2023-30861" ],
  "summary" : "Flask vulnerable to possible disclosure of permanent session cookie due to missing Vary: Cookie header",
  "details" : "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.\n\n1. The application must be hosted behind a caching proxy that does not strip cookies or ignore responses with cookies.\n2. The application sets [`session.permanent = True`](https://flask.palletsprojects.com/en/2.3.x/api/#flask.session.permanent).\n2. The application does not access or modify the session at any point during a request.\n4. [`SESSION_REFRESH_EACH_REQUEST`](https://flask.palletsprojects.com/en/2.3.x/config/#SESSION_REFRESH_EACH_REQUEST) is enabled (the default).\n5. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n\nThis 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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "Flask"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.3.0"
      }, {
        "fixed" : "2.3.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "Flask"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.2.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/pallets/flask/security/advisories/GHSA-m2qf-hxjv-5gpq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-30861"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pallets/flask/commit/70f906c51ce49c485f1d355703e9cc3386b1cc2b"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pallets/flask/commit/afd63b16170b7c047f5758eb910c416511e9c965"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/pallets/flask"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pallets/flask/releases/tag/2.2.5"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pallets/flask/releases/tag/2.3.2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/flask/PYSEC-2023-62.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2023/08/msg00024.html"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20230818-0006"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2023/dsa-5442"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-539" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-05-01T19:22:20Z",
    "nvd_published_at" : "2023-05-02T18:15:52Z"
  }
}