Firefox before 1.0 and Mozilla before 1.7.5 display the secure site lock icon when a view-source: URL references a secure SSL site while an insecure page is being loaded, which could facilitate phishing attacks.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11016
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A100054
https://exchange.xforce.ibmcloud.com/vulnerabilities/19169
https://bugzilla.mozilla.org/show_bug.cgi?id=262689
http://www.securityfocus.com/bid/12407
http://www.redhat.com/support/errata/RHSA-2005-335.html