CVE-2011-0242 in Safari
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in WebKit in Apple Safari before 5.0.6 allows remote attackers to inject arbitrary web script or HTML via vectors involving a URL that contains a username.
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Analysis
by VulDB Data Team • 01/26/2025
The vulnerability described in CVE-2011-0242 represents a cross-site scripting flaw within Apple Safari's WebKit rendering engine that existed prior to version 5.0.6. This security weakness falls under the broader category of CWE-79, which specifically addresses cross-site scripting vulnerabilities where improper validation of user-supplied data allows malicious code execution. The flaw manifests when Safari processes URLs containing usernames, creating an environment where attackers can inject arbitrary web scripts or HTML content that executes within the context of the victim's browser session.
The technical mechanism behind this vulnerability involves WebKit's handling of URL parsing and username extraction within web addresses. When Safari encounters a URL with a username component, the browser's rendering engine fails to properly sanitize or escape the username data before incorporating it into the page's execution context. This insufficient input validation creates a pathway for attackers to craft malicious URLs that, when visited by victims, execute unintended code within the browser's security boundaries. The vulnerability specifically leverages the way Safari processes authentication credentials embedded within URLs, where the username portion becomes part of the rendering pipeline without adequate security measures.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to perform various malicious activities including session hijacking, data theft, and redirection to malicious sites. An attacker could craft a URL containing a malicious script within the username field that would execute when a user clicks on the link, potentially stealing cookies, credentials, or other sensitive information. The vulnerability's remote exploitation capability means that users could be compromised simply by visiting a malicious website or clicking on a crafted link, making it particularly dangerous in phishing scenarios and social engineering attacks. This flaw represents a significant threat to user privacy and security, as it allows unauthorized code execution in the context of a user's authenticated session.
Mitigation strategies for CVE-2011-0242 primarily focus on updating to Safari version 5.0.6 or later, which includes the necessary patches to properly sanitize URL username components. Organizations should implement comprehensive browser security policies that enforce regular updates and maintain awareness of vulnerable software versions. Network administrators can deploy web application firewalls and content filtering solutions to detect and block malicious URLs containing suspicious script content. The vulnerability also highlights the importance of following secure coding practices such as those outlined in the OWASP Top Ten and the CERT/CC secure coding guidelines, particularly regarding input validation and output encoding. Additionally, user education regarding URL inspection and suspicious link behavior remains crucial in defending against exploitation attempts that leverage this type of XSS vulnerability. This case demonstrates the critical need for continuous security monitoring and prompt patch management to prevent exploitation of rendering engine vulnerabilities that can compromise user sessions and data integrity.