Apple Safari 4.0.3 does not properly block javascript: and data: URIs in Refresh headers in HTTP responses, which allows remote attackers to conduct cross-site scripting (XSS) attacks via vectors related to (1) injecting a Refresh header that contains a javascript: URI, (2) entering a javascript: URI when specifying the content of a Refresh header, (3) injecting a Refresh header that contains JavaScript sequences in a data:text/html URI, or (4) entering a data:text/html URI with JavaScript sequences when specifying the content of a Refresh header.