Path traversal symlink - WEBrick
A path traversal issue was observed in WEBrick ( WEBrick/1.4.2 (Ruby/2.6.3/2019-04-16)) via symlink. WEBrick serves static page for the current directory once enabled, however using symlink attacker could view data outside the hosted/running directory.
Steps to reproduce:
ln -s ../../ symlnk
ruby -run -ehttpd . -p8080
This would allow the attacker to view sensitive data outside the root/running directory.
We can probably educate users about this behavior in the WebBrick documentation and providing a flag/parameter to disable/enable following symlinks.