CVE-2010-1236 in Chrome
Summary
by MITRE
The protocolIs function in platform/KURLGoogle.cpp in WebCore in WebKit before r55822, as used in Google Chrome before 4.1.249.1036 and Flock Browser 3.x before 3.0.0.4112, does not properly handle whitespace at the beginning of a URL, which allows remote attackers to conduct cross-site scripting (XSS) attacks via a crafted javascript: URL, as demonstrated by a \x00javascript:alert sequence.
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Analysis
by VulDB Data Team • 05/04/2026
The vulnerability identified as CVE-2010-1236 represents a critical cross-site scripting flaw within the WebKit rendering engine's URL parsing mechanism. This issue specifically affects the protocolIs function located in platform/KURLGoogle.cpp within WebCore, which is the core component responsible for handling web protocols and URL manipulation in WebKit-based browsers. The vulnerability exists in WebKit versions prior to revision r55822 and impacts major browser implementations including Google Chrome versions before 4.1.249.1036 and Flock Browser 3.x versions before 3.0.0.4112. The flaw demonstrates how improper input validation can lead to severe security consequences in web browser implementations.
The technical root cause of this vulnerability stems from the protocolIs function's inadequate handling of leading whitespace characters within URL strings. When a maliciously crafted javascript: URL contains whitespace at its beginning, the function fails to properly sanitize or validate this input before processing. This parsing error creates a condition where attackers can inject malicious JavaScript code that bypasses normal security checks. The vulnerability specifically exploits the fact that the URL parser does not normalize whitespace characters at the start of URLs, allowing attackers to prepend whitespace to javascript: URLs and execute arbitrary code in the context of the victim's browser session. This behavior violates the fundamental security principle of input sanitization and demonstrates a classic example of improper validation of input data.
The operational impact of this vulnerability is severe and directly enables remote code execution through cross-site scripting attacks. Attackers can craft malicious URLs containing whitespace-prefixed javascript: sequences that, when processed by vulnerable browsers, execute arbitrary JavaScript code within the victim's browser context. This allows for complete compromise of user sessions, data theft, credential harvesting, and potential redirection to malicious sites. The vulnerability particularly affects web applications that rely on user-provided URLs or that do not properly validate URL inputs, making it a significant threat to web application security. The attack vector is particularly dangerous because it can be delivered through various means including phishing emails, malicious websites, or compromised web applications that accept user input without proper validation.
This vulnerability maps directly to CWE-79, which describes Cross-Site Scripting flaws, and aligns with ATT&CK technique T1059.007 for JavaScript execution. The flaw represents a failure in the input validation and sanitization processes that should occur at multiple layers of the application stack. Security professionals should consider this vulnerability as part of broader XSS attack patterns and implement comprehensive defenses including Content Security Policy headers, proper input validation, and regular security updates. The remediation approach involves updating to patched versions of WebKit, Google Chrome, and Flock Browser where the protocolIs function properly handles whitespace characters in URL parsing. Organizations should also implement additional security controls such as web application firewalls and regular security audits to prevent exploitation of similar vulnerabilities in other components of their web infrastructure.
The exploitation of this vulnerability demonstrates how seemingly minor parsing inconsistencies in browser engines can lead to significant security implications. This flaw underscores the critical importance of thorough input validation and the need for comprehensive security testing of core browser components. The vulnerability serves as a reminder that even fundamental parsing functions require rigorous security review, as they form the foundation upon which all web security mechanisms depend. Proper patch management and timely updates are essential to protect against such vulnerabilities that can be exploited to gain unauthorized access to user sessions and execute malicious code within browser contexts.