.svg isn't recognised by Moodle as a file type - forum search for svg doesn't seem to reveal much. I've asked about this issue here on Moodle Matters @ UC and been discussing work-arounds.
Given that .svg is a recommended file format for diagrams etc. and is widely used e.g., by the Wikimedia Foundation it would be desirable from a usability POV for Moodle to also deal with any security issues and allow .svg files.
Moodle in English -> General help Usability: .svg not recognised as an image file type
by James Neill -