Sleipnir 4 Black Edition for Mac 4.5.3 and earlier and Sleipnir 4 for Mac 4.5.3 and earlier (Mac App Store) may allow a remote attacker to spoof the URL display via a specially crafted webpage.
Fenrir Sleipnir 2.9.6 and earlier does not prevent interaction between web script and the clipboard, which allows remote attackers to read or modify the clipboard contents via a crafted web site.