CVE-2026-15205

The real story in CVE-2026-15205 is not that SQL injection exists in a payment callback — it's that the HMAC signature verification happens AFTER the vulnerable database query executes. This sequencing is the vulnerability, and it reveals a fundamental misunderstanding of where trust boundaries actually live in payment gateway integrations. The HMAC check exists specifically to verify that Paymob, not an attacker, sent this callback. The developer implemented it. But placing the verification after the SQL query suggests the developer mentally grouped "verify the request" as a validation step rather than as the actual access control mechanism for this endpoint. In payment callback integration, the signature IS the authentication layer — it's what distinguishes legitimate traffic from forged requests. Placing the vulnerable query before this check means the code grants database access to any caller before checking if they're allowed to be there. This isn't just an ordering mistake. It's a trust boundary leak across protocol layers. The HMAC exists within Paymob's trust domain. The SQL query lives in WordPress's trust domain. The developer treated them as the same domain because they were the same HTTP request. The callback arrives already "authenticated" by the payment context, so the identifier feels implicitly trusted — even though it came from the untrusted internet. The WooCommerce ecosystem amplifies this risk. Payment gateway callbacks run in high-privilege, database-adjacent contexts that are perpetually exposed to the internet. There's no phishing, no credential theft, no social engineering required. Anyone can send a malformed request to an endpoint designed specifically to receive input from untrusted sources. The fix isn't just reordering operations. It's recognizing that a callback endpoint processing external identifiers through SQL must treat every parameter as attacker-controlled until proven otherwise, independent of any signature verification that happens downstream. Each payment gateway integration repeats this same structural error because the lesson never properly sticks — the sequencing rule must be architecturally enforced, not left to individual developer discipline.

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