Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a path traversal vulnerability in the squirrelmail_usercopy plugin. With the file based backend, the source path was built from the login name without rejecting path separators, so a login name containing a slash could cause files outside the configured squirrelmail_data_dir to be read and imported. Upstream fixed this in the commit “Fix unsafe use of a login name in SquirrelMail import file path”, which rejects login names containing a slash.