Craft is a content management system. Versions of Craft CMS on the 4.x branch prior to 4.14.13 and on the 5.x branch prior to 5.6.16 contains a potential remote code execution vulnerability via Twig SSTI. One must have administrator access and `ALLOW_ADMIN_CHANGES` must be enabled for this to work. Users should update to the patched versions 4.14.13 or 5.6.15 to mitigate the issue.