The TiendaCrypto para WooCommerce WordPress plugin through 1.2.1 does not correctly verify the authenticity of its payment webhook, validating the request signature against a key that is always empty, which allows unauthenticated attackers to forge webhook notifications and mark arbitrary WooCommerce orders as paid on web servers that preserve request header case.
The product does not verify, or incorrectly verifies, the cryptographic signature for data.