Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Summary

gatsby-plugin-sharp is a plugin for the gatsby framework which exposes functions built on the Sharp image processing library. The gatsby-plugin-sharp plugin versions prior to 4.25.1,5.x prior to 5.8.1, and 5.9.0-next.0 contains a path traversal vulnerability exposed when running the Gatsby develop server ("gatsby develop"). It should be noted that by default gatsby develop is only accessible via the localhost 127.0.0.1, and one would need to intentionally expose the server to other interfaces to exploit this vulnerability by using server options such as --host 0.0.0.0, -H 0.0.0.0, or the GATSBY_HOST=0.0.0.0 environment variable. Attackers exploiting this vulnerability will have read access to all files within the scope of the server process. A patch has been introduced in gatsby-plugin which mitigates the issue by ensuring that included paths remain within the project directory. As stated above, by default gatsby develop is only exposed to the localhost 127.0.0.1. For those using the develop server in the default configuration no risk is posed. If other ranges are required, preventing the develop server from being exposed to untrusted interfaces or IP address ranges would mitigate the risk from this vulnerability. Users are non the less encouraged to upgrade to a safe version.