CVE-2026-45414: Decidim JWT-backed Authentication Can Be Replayed Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-r3v7-5x4c-c69q",
  "modified" : "2026-07-13T17:16:57Z",
  "published" : "2026-07-13T17:16:56Z",
  "aliases" : [ "CVE-2026-45414" ],
  "summary" : "Decidim: JWT-backed authentication can be replayed across organizations",
  "details" : "## Description\n\nA JWT issued to an Org 1 account is accepted on the Org 2 API and can read the admin-only GraphQL `participantDetails` field for an Org 2 participant. The same trust-boundary problem also affects API-user authentication: an Org 1 API user can use a JWT on the Org 1 host and replay that JWT to the Org 2 API to read Org 2 participant personal data and reach Org 2's `proposal.answer` mutation path.\n\n##  Technical description\n\nThe current host selects the Decidim organization context, but JWT-backed API authentication is not sufficiently bound to\nthat host organization. As a result, the API can process a request in Org 2's context while still trusting an authenticated\nprincipal from Org 1.\n\nReproduction steps:\n\n1. Use an API key provided by the system administrator that is assigned to organization 1 to create the JWT token or\nget the JWT token shown in the response when logged in as the organization admin.\n\n<img width=\"1080\" height=\"1119\" alt=\"decidim-jwt-01\" src=\"https://github.com/user-attachments/assets/6195a250-faef-41d5-8f64-4d77d4077e96\" />\n\n\n2. When using this JWT token it is possible to retrieve details from other organisations. Notice the change of the host header in the request below to that of another tenant `org2.localhost:3001`\n \n<img width=\"1085\" height=\"1047\" alt=\"decidim-jwt-02\" src=\"https://github.com/user-attachments/assets/d40825e3-0d36-44f3-bede-86d247bbe6d0\" />\n\nNote that using a participant-generated JWT did not allow showing these results.\n\n### Impact\n\nA JWT issued for one organization can be replayed successfully against another organization's API and used to retrieve sensitive details from that organization.\n\n### Patches\n\nSee https://github.com/decidim/decidim/pull/16673 and https://github.com/decidim/decidim/pull/16756\n\n### Workarounds\n\nDisable JWT credentials on system panel (`/system`) \n\n### References\n\nOWASP A01:2021 Broken Access Control\n\n### Credits\n\nThis issue was discovered in a security audit organized by the [Decidim Association](https://decidim.org) and made by [Radically Open Security](https://www.radicallyopensecurity.com/) against Decidim financed by [NGI](https://ngi.eu/).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "decidim"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.31.5"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "decidim"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.32.0.rc1"
      }, {
        "fixed" : "0.32.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/decidim/decidim/security/advisories/GHSA-r3v7-5x4c-c69q"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/decidim/decidim/pull/16673"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/decidim/decidim/pull/16756"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/decidim/decidim"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-287" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-13T17:16:56Z",
    "nvd_published_at" : null
  }
}