CVE-2010-0053 in Safari
Summary
by MITRE
Use-after-free vulnerability in WebKit in Apple Safari before 4.0.5 allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via vectors related to the run-in Cascading Style Sheets (CSS) display property.
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Analysis
by VulDB Data Team • 05/02/2026
The CVE-2010-0053 vulnerability represents a critical use-after-free flaw within Apple Safari's WebKit rendering engine that existed prior to version 4.0.5. This vulnerability specifically targets the handling of the run-in CSS display property, which is a lesser-used CSS element that creates inline elements that behave like block-level elements. The flaw occurs when the browser processes web content containing malicious CSS declarations that trigger improper memory management during the rendering process.
The technical exploitation of this vulnerability relies on the improper handling of memory allocation and deallocation when processing the run-in CSS display property. When a web page contains crafted CSS code that utilizes this specific display property in combination with other CSS elements, the WebKit engine fails to properly manage the memory references, leading to a situation where freed memory locations are accessed after they have been deallocated. This memory management error creates a use-after-free condition that can be leveraged by remote attackers to execute arbitrary code or cause application crashes.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to include full remote code execution capabilities. Attackers can craft malicious web pages that, when loaded in Safari, trigger the memory corruption issue and subsequently execute malicious payloads within the browser's security context. The vulnerability affects users who browse the internet with Safari versions prior to 4.0.5, making it particularly dangerous as it targets a widely used browser on macOS systems. The attack vector is entirely remote, requiring no local access or user interaction beyond visiting a malicious website, which significantly increases the attack surface.
This vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software systems, and demonstrates how improper memory management can lead to severe security implications. The ATT&CK framework categorizes this vulnerability under T1059 for command and scripting interpreter execution, as successful exploitation would allow attackers to execute arbitrary code on target systems. The vulnerability also reflects common issues in browser security where CSS processing engines are not adequately hardened against malformed inputs, making it a prime example of how seemingly benign web technologies can become attack vectors when not properly validated. Security researchers have noted that this type of vulnerability is particularly challenging to detect and prevent, as it requires deep understanding of both the browser's rendering engine and the underlying memory management systems. The remediation for this vulnerability required Apple to implement proper memory management controls within the WebKit engine's CSS parser, ensuring that all memory references are properly tracked and validated before and after deallocation. Organizations should prioritize updating Safari to version 4.0.5 or later to mitigate this risk, as the vulnerability represents a significant threat to user security and system integrity.