CVE-2017-11342 in LibSass
Summary
by MITRE
There is an illegal address access in ast.cpp of LibSass 3.4.5. A crafted input will lead to a remote denial of service attack.
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Analysis
by VulDB Data Team • 09/08/2025
The vulnerability identified as CVE-2017-11342 represents a critical memory access issue within the LibSass library version 3.4.5, specifically within the ast.cpp file. This flaw constitutes a remote denial of service vulnerability that can be exploited through carefully crafted input sequences. The issue arises from improper handling of memory addresses during the parsing and processing of Sass stylesheet code, creating a scenario where malicious input can trigger unauthorized memory access patterns that lead to application instability and potential system crashes.
The technical root cause of this vulnerability lies in the improper validation and handling of memory addresses within the abstract syntax tree (AST) processing components of LibSass. When the library encounters malformed or specially crafted Sass input, the ast.cpp module fails to properly validate memory references, resulting in illegal address access operations. This type of vulnerability falls under CWE-125, which describes out-of-bounds read conditions, and represents a classic example of memory safety issues that can be exploited to cause denial of service attacks. The vulnerability demonstrates characteristics consistent with memory corruption flaws that can be leveraged by attackers to disrupt service availability.
The operational impact of CVE-2017-11342 extends beyond simple service disruption, as it can affect any system or application that relies on LibSass for stylesheet processing. This includes web applications, static site generators, content management systems, and development tools that utilize Sass preprocessing capabilities. Attackers can exploit this vulnerability remotely by submitting malicious Sass code to systems that process such input, potentially causing applications to crash, become unresponsive, or consume excessive system resources. The vulnerability affects a wide range of platforms and applications that depend on LibSass for CSS compilation, making it particularly dangerous in production environments where availability is critical.
Mitigation strategies for this vulnerability should focus on immediate patching of affected LibSass versions, with the recommended solution being an upgrade to LibSass version 3.5.0 or later where the memory access issues have been addressed. Organizations should implement input validation measures to filter potentially malicious Sass code before processing, though this approach is less reliable than proper patching. Security monitoring should include detection of unusual resource consumption patterns that might indicate exploitation attempts. The vulnerability's classification under ATT&CK technique T1499.004, which covers network denial of service, highlights the importance of implementing proper access controls and input sanitization measures. Additionally, system administrators should consider implementing application whitelisting and sandboxing techniques to limit the impact of potential exploitation attempts.