Description

A flaw was found in Red Hat Quay's Stripe billing webhook handler. This vulnerability allows an unauthenticated attacker to forge billing events by sending crafted JSON requests to the `/webhooks/stripe` endpoint without validating the Stripe-Signature header. Successful exploitation can lead to the unauthorized resetting of a namespace's build quota to its maximum and trigger unsolicited billing emails to namespace administrators.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.9",
  "pubDate": "2026-08-14T23:16:34.490Z",
  "pubdate": "2026-08-14T23:16:34.490Z",
  "executiveSummary": "A critical vulnerability exists within Red Hat Quay's Stripe billing webhook handler, specifically affecting the endpoint responsible for processing external billing events. The security flaw stems from an absolute lack of cryptographic signature validation on incoming HTTP requests destined for the designated handling route. Specifically, the system fails to inspect and verify the integrity and authenticity provided by the mandatory Stripe-Signature header prior to parsing the payload. This oversight introduces a severe authentication bypass vulnerability, enabling unauthenticated remote threat actors to interact directly with the billing infrastructure. By leveraging this exposure, an attacker can craft arbitrary, malicious JSON payloads designed to mimic legitimate billing notifications and transmit them directly to the vulnerable listener. Successful exploitation of this flaw grants unauthorized entities the capability to manipulate sensitive namespace resource limits, resulting in the malicious elevation of build quotas to their absolute maximum thresholds. Furthermore, fraudulent events can be orchestrated to dispatch unsolicited, potentially confusing or alarming billing-related electronic mail notifications directly to targeted namespace administrators. The risk implications encompass potential resource exhaustion, service degradation, and administrative disruption, all achieved entirely without prior system authentication or valid cryptographic credentials.",
  "technicalDetails": "The vulnerability resides in the webhook integration subsystem of Red Hat Quay, specifically within the Stripe billing webhook handler servicing the /webhooks/stripe endpoint. The fundamental root cause of the security defect is the omission of cryptographic verification logic required to authenticate incoming webhook payloads against the expected secret shared between the application and the payment processing provider. In a secure implementation, endpoints processing webhook events must intercept the raw payload alongside the Stripe-Signature HTTP header, utilizing a constant-time comparison algorithm and a secret key to validate that the message originated from the authorized external service. In this vulnerable component, the application accepts incoming HTTP POST requests containing arbitrary JSON data directly at the /webhooks/stripe endpoint without enforcing these validation checks. Consequently, the network exposure of this endpoint is public-facing, requiring no authentication credentials, session tokens, or specialized privilege levels to interact with. The attack flow proceeds as follows: an unauthenticated attacker crafts a malicious HTTP POST request containing a manipulated JSON body designed to simulate a specific Stripe billing event, such as a subscription tier upgrade or payment confirmation. The attacker transmits this crafted payload directly to the network-exposed /webhooks/stripe URL over standard web protocols. Because the handler completely bypasses validation of the Stripe-Signature header, the application proceeds to parse the untrusted JSON input as a legitimate billing event. The backend logic then processes the instructions contained within the forged payload, executing administrative state changes tied to the targeted namespace. The direct post-exploitation impact includes the unauthorized resetting of the specified namespace's build quota to its maximum allowable limit, thereby altering resource allocation boundaries without authorization. Additionally, the execution of the forged event triggers the internal notification dispatch mechanism, resulting in unsolicited billing emails being transmitted to the administrative users associated with the affected namespace. This vector demonstrates a complete failure in input trust boundaries and cryptographic enforcement for asynchronous API endpoints."
}