The tabbed browsing feature in Apple Safari 3 before Beta Update 3.0.4 on Windows, and Mac OS X 10.4 through 10.4.10, allows remote attackers to spoof HTTP authentication for other sites and possibly conduct phishing attacks by causing an authentication sheet to be displayed for a tab that is not active, which makes it appear as if it is associated with the active tab.
CWE-287 - Improper Authentication
Improper (or broken) authentication attacks are widespread, and have accounted for many of the worst data breaches in recent years. Improper authentication attacks are a class of vulnerabilities where an attacker impersonates a legitimate user by exploiting weaknesses in either session management or credential management to gain access to the user’s account. This can result in disclosure of sensitive information, and can lead to system compromise, theft, identity theft, and fraud.