Unauthenticated Spree Commerce users can access all guest addresses
Date: 2026-02
Affected: rubygems/spree_api, rubygems/spree_api, rubygems/spree_api
Attack vector: auth-bypass
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-25758
CWE: CWE-284
CWE-639

### Summary A critical IDOR vulnerability exists in Spree Commerce's guest checkout flow that allows any guest user to bind arbitrary guest addresses to their order by manipulating address ID parameters. This enables unauthorized access to other guests' personally identifiable information (PII) including names, addresses and phone numbers. The vulnerability bypasses existing ownership validation checks and affects all guest checkout transactions. ### Impact This issue may lead to disclosure of PII of guest users (including names, addresses and phone numbers). ### Unauthenticated users can access all guest addresses (`GHSL-2026-027`) The vulnerability stems from incomplete authorization validation in Spree's checkout address assignment logic. While nested address attributes (`bill_address_attributes[id]` and `ship_address_attributes[id]`) are properly validated through `validate_address_ownership`, plain ID parameters (`bill_address_id` and `ship_address_id`) bypass this check entirely. Since Spree's address IDs are sequential numbers, an attacker might get all guest addresses by simply enumerating over them. ### Affected Code Components 1. **Permitted Attributes** ([`core/lib/spree/permitted_attributes.rb:92–96`](https://github.com/spree/spree/blob/1341623f2ae92685cdbe232885bf5808fc8f9ca8/core/lib/spree/permitted_attributes.rb#L92-L96)) - Allows `bill_address_id` and `ship_address_id` as permitted parameters without validation 2. **Checkout Update** ([`core/app/model


Mitigations:

Architectural layers (MAESTRO):