CVE-2010-1749 in Safari
Summary
by MITRE
Use-after-free vulnerability in WebKit in Apple Safari before 5.0 on Mac OS X 10.5 through 10.6 and Windows, and before 4.1 on Mac OS X 10.4, allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via vectors related to the Cascading Style Sheets (CSS) run-in property and multiple invocations of a destructor for a child element that has been referenced multiple times.
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Analysis
by VulDB Data Team • 04/10/2025
This vulnerability represents a critical use-after-free condition within WebKit's CSS processing engine that affects Apple Safari browsers across multiple operating systems. The flaw specifically manifests when handling the CSS run-in property, a less commonly used CSS display property that causes an element to behave as a run-in element. The vulnerability occurs due to improper memory management during the processing of CSS stylesheets containing this property, creating a scenario where memory allocated to an object is freed while references to it still exist.
The technical exploitation involves a complex interaction between CSS parsing and JavaScript object lifecycle management within WebKit's rendering engine. When a web page contains CSS rules using the run-in property with multiple nested elements, the browser's memory management system fails to properly track object references during the destructor invocation process. This creates a situation where a destructor for a child element gets called multiple times on the same memory location, leading to a use-after-free condition. The vulnerability is particularly dangerous because it can be triggered through crafted CSS content delivered via web pages, making it a prime candidate for remote code execution attacks.
The operational impact of this vulnerability extends across multiple platform versions, affecting Mac OS X 10.5 through 10.6 and Windows systems running Safari versions prior to 5.0, as well as Mac OS X 10.4 systems with Safari versions before 4.1. Attackers can leverage this weakness to execute arbitrary code with the privileges of the browser process, potentially leading to complete system compromise. The vulnerability also enables denial of service attacks that can crash the Safari browser application, disrupting user sessions and potentially providing a foothold for further exploitation. This makes it particularly attractive to threat actors seeking to establish persistent access or conduct large-scale attacks against vulnerable systems.
Security researchers have classified this vulnerability under CWE-416, which specifically addresses use-after-free conditions in memory management. The attack pattern aligns with ATT&CK technique T1059.007 for JavaScript execution and T1059.001 for command and scripting interpreter usage, as attackers can leverage the compromised browser to execute malicious code. Mitigation strategies should focus on immediate patch deployment for all affected Safari versions, implementing web application firewalls to filter suspicious CSS content, and employing browser security enhancements such as address space layout randomization and data execution prevention. Additionally, organizations should consider implementing content security policies and restricting access to potentially malicious websites through network-level controls to reduce the attack surface.