From securityboulevard.com
While unpatched installations of Magento 2 contain many vulnerabilities, I’m going to focus my attention on Magento 1 for this article. This is because Magento 2 provides regularly updated patches for many of the most common vulnerabilities targeting the platform. While Magento 1 also contains patches for many known vulnerabilities, those patches are not currently maintained.
Magento 1 reached its end-of-support on June 30, 2020. When Magento 2 was released, the focus was to improve security, include speed improvements, support the latest PHP installations, include SEO optimizations and provide a more user-friendly interface.