The package is an Express middleware that normalises routes by stripping any final slash, redirecting, for example, bookings/latest/
to bookings/latest
. However, it does not validate the path it redirects to in any way. In particular, if the path starts with two slashes (or two backslashes, or a slash and a backslash, etc.) it may redirect to a different domain.
Consider the example from the docs. Assume we have run it and started a server on localhost:3000
, then visiting localhost:3000///github.com/
redirects you to https://github.com.
This vulnerability is currently un-patched in the slashify
package so there is no known safe version of this package. Discontinuing use of slashify
is recommended.