CVE-2026-41432: LLM Gateway Stripe Webhook Flaw Allows Quota Forgery

title: CVE-2026-41432: LLM Gateway Stripe Webhook Quota Forgery
id: scw-2026-05-08-ai-1
status: experimental
level: high
description: |
  Detects an unauthenticated attacker attempting to forge Stripe webhook events by sending POST requests to the webhook endpoint. This specific rule looks for requests to the '/stripe/webhook' URI with a 200 status code, and a hypothetical query parameter ('quota_override' or 'forged_event') that might be used in an attempt to credit arbitrary quota. This targets CVE-2026-41432, which allows quota forgery without payment.
author: SCW Feed Engine (AI-generated)
date: 2026-05-08
references:
  - https://shimiscyberworld.com/posts/nvd-CVE-2026-41432/
tags:
  - attack.initial_access
  - attack.t1190
logsource:
    category: webserver
detection:
  selection:
      cs-uri|contains:
          - '/stripe/webhook'
      cs-method:
          - 'POST'
      sc-status:
          - '200'
      # This is a placeholder for a specific payload pattern that would be indicative of quota forgery.
      # In a real-world scenario, this would require reverse engineering the webhook payload structure
      # and identifying specific parameters or values used to manipulate quota. 
      # For example, if the webhook payload contained a specific 'EventType' and 'amount' that bypassed checks:
      # "EventType": "charge.succeeded"
      # "data.object.amount_received": "0"
      # "data.object.metadata.quota_added": "10000"
      # Since we cannot know the exact payload without more info, we'll use a generic placeholder for demonstration.
      # A real rule would need specific payload inspection capabilities not directly exposed in the provided fields.
      # For the purpose of this example, we'll assume a hypothetical parameter that might be manipulated.
      # If the webhook handler is vulnerable to forging events, it might accept a POST request with specific parameters
      # that are not typically part of a legitimate Stripe event but are processed by the vulnerable gateway.
      # Example: A forged event might include a parameter like 'is_test_event' or a specific 'source' field.
      # Without specific payload details, detecting this via standard webserver logs is challenging.
      # However, if the gateway logs the request body or specific parameters in a query string for POST requests,
      # that would be the place to look. Assuming 'cs-uri-query' might capture some parameters if not in body:
      cs-uri-query|contains:
          - 'quota_override'
          - 'forged_event'
  condition: selection
falsepositives:
  - Legitimate administrative activity

Source: Shimi's Cyber World · License & reuse