CVE-2025-32378: Shopware default newsletter opt-in settings allow for mass sign-up abuse

Currently the default settings for double-opt-in allow for mass unsolicited newsletter sign-ups without confirmation.

Default settings are:

Newsletter: Double Opt-in - active

Newsletter: Double opt-in for registered customers - disabled

Log-in & sign-up: Double opt-in on sign-up - disabled

With these settings, anyone can register an account on the shop using any e-mail-address and then check the check-box in the account page to sign up for the newsletter. The recipient will receive two mails confirming registering and signing up for the newsletter, no confirmation link needed to be clicked for either. In the backend the recipient is set to “instantly active”.