CVE-2026-94462: Spree Broken Access Control Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4825-p4xm-pcf2",
  "modified" : "2026-09-22T20:40:30Z",
  "published" : "2026-09-22T20:40:30Z",
  "aliases" : [ "CVE-2026-94462" ],
  "summary" : "Spree: Broken Access Control in `PATCH /api/v3/store/carts/:id/associate` (IDOR)",
  "details" : "## Summary\n\nThe Store API v3 endpoint `PATCH /api/v3/store/carts/:id/associate` binds a guest cart to the authenticated caller without verifying possession of that cart. It locates the cart by prefixed ID only — `current_store.carts.where(user: [nil, current_user]).find_by_prefix_id!(params[:id])` — and omits the `authorize!(:update, @cart, cart_token)` check that every other action in the controller performs via `CartResolvable`. Because prefixed IDs are a reversible Sqids encoding of the auto-increment primary key (obfuscation, not a token), an authenticated customer can name arbitrary guest cart IDs, take them over, and read the checkout addresses stored on them. This is broken access control / IDOR, reachable by any low-privilege registered user.\n\n## Severity\n\nRequires an authenticated store account and depends on target guest carts already carrying an address and not yet being associated, on a store not running in `login_required` mode. Confidentiality impact is the driver (guest checkout PII); integrity impact is limited and recoverable (cart reassignment + email overwrite on an in-progress cart). Not Critical: the action is gated behind authentication (`PR:L`, not `PR:N`) and constrained by cart state, so it is not anonymously exploitable.\n\n## Details\n\n**Root cause:** `associate` skips the cart-possession check its sibling actions enforce and trusts a guessable identifier as the sole locator.\n\n**Entry point.** `Spree::Api::V3::Store::CartsController#associate` (`carts_controller.rb:88-96`), guarded only by `prepend_before_action :require_authentication!, only: [:index, :associate]`. That requires the *caller* be authenticated; it does not tie the request to a specific guest cart.\n\n```ruby\n# spree/api/app/controllers/spree/api/v3/store/carts_controller.rb:88-96\n# PATCH /api/v3/store/carts/:id/associate\ndef associate\n  @cart = find_cart_for_association\n\n  result = Spree.cart_associate_service.call(guest_order: @cart, user: current_user, guest_only: true)\n\n  if result.success?\n    render_cart\n  else\n    render_service_error(result.error.to_s)\n  end\nend\n```\n\n**Missing check.** `find_cart_for_association` (`carts_controller.rb:177-178`) resolves any guest cart (`user IS NULL`) in the store by ID with no `authorize!(..., cart_token)`. Contrast `CartResolvable#find_cart!`, which binds the token.\n\n```ruby\n# spree/api/app/controllers/spree/api/v3/store/carts_controller.rb:177-178\ndef find_cart_for_association\n  current_store.carts.where(user: [nil, current_user]).find_by_prefix_id!(params[:id])\nend\n```\n\n**Identifier.** `prefixed_id` is `\"cart_\" + SQIDS.encode([id])` with `SQIDS = Sqids.new(min_length: 10)` (`prefixed_id.rb:17,56`) — default alphabet, no salt, no blocklist. Sqids is non-cryptographic and reversible, so candidate IDs are derivable offline from sequential primary keys.\n\n```ruby\n# spree/core/app/models/concerns/spree/prefixed_id.rb:17-56\nSQIDS = Sqids.new(min_length: 10)\n\ndef prefixed_id\n  return nil unless id.present?\n\n  \"#{self.class._prefix_id_prefix}_#{Spree::PrefixedId::SQIDS.encode([id])}\"\nend\n```\n\n**Data flow.** `Spree.cart_associate_service.call(guest_order: @cart, user: current_user, guest_only: true)` reassigns the owner and overwrites email, preserving existing addresses via `bill_address ||= / ship_address ||=`. `render_cart` then serializes `billing_address`/`shipping_address` (first_name, last_name, address1, address2, city, postal_code, phone, company) back to the caller.\n\n## PoC\n\n**Preconditions:** attacker holds an ordinary store account (self-service registration) and the store's publishable key (a front-end credential, present in any headless storefront bundle); one or more guest carts carry checkout addresses; store is not in `login_required` mode.\n\n1. Authenticate: `POST /api/v3/store/auth/login` → attacker JWT.\n2. Derive candidate IDs offline: `\"cart_\" + Sqids.encode([n])` for a range of `n`.\n3. For each candidate: `PATCH /api/v3/store/carts/<id>/associate` with the attacker JWT. A hit returns `200` with the victim's `billing_address`/`shipping_address`; non-guest or missing carts return `404`/`422`.\n\n## Impact\n\n**Confidentiality:** an authenticated attacker can enumerate guest cart IDs and read checkout PII (name, street, postal code, phone) on carts they don't own. **Integrity:** limited and recoverable — each call reassigns the guest cart and overwrites its email, disrupting the original guest's in-progress cart. Requires a registered account, so not anonymously exploitable.\n\n## Remediation\n\nUpdate to Spree 5.4.4 or 5.5.4. Your storefront, based on https://github.com/spree/storefront, doesn't need any updates because it has always sent a cart token when associating carts; this is a backend issue.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "spree_api"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.4.0"
      }, {
        "fixed" : "5.4.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "spree_api"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.5.0"
      }, {
        "fixed" : "5.5.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/spree/spree/security/advisories/GHSA-4825-p4xm-pcf2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/spree/spree/pull/14314"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/spree/spree/commit/8834230a1f47bb5988f23f45dbd162776cf592bd"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/spree/spree/commit/af0d1a2d582a60d179de65b7d3ea024cb26426a8"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/spree/spree"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/spree/spree/releases/tag/v5.4.4"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/spree/spree/releases/tag/v5.5.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-22T20:40:30Z",
    "nvd_published_at" : null
  }
}