CVE-2016-1684 in tvOS
Summary
by MITRE
numbers.c in libxslt before 1.1.29, as used in Google Chrome before 51.0.2704.63, mishandles the i format token for xsl:number data, which allows remote attackers to cause a denial of service (integer overflow or resource consumption) or possibly have unspecified other impact via a crafted document.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/06/2022
The vulnerability identified as CVE-2016-1684 represents a critical flaw in the libxslt library's handling of numeric formatting within xsl:number elements. This issue affects Google Chrome versions prior to 51.0.2704.63 and exists in libxslt versions before 1.1.29. The vulnerability stems from improper validation and processing of the i format token in xsl:number data, which creates opportunities for malicious actors to exploit the system through crafted XML documents. The flaw manifests when the library processes numeric values that exceed normal computational bounds, leading to potential system instability and resource exhaustion.
The technical implementation of this vulnerability involves the manipulation of the xsl:number element's formatting specification, specifically the i format token which represents lowercase Roman numerals. When processing documents containing maliciously crafted numeric values, the libxslt library fails to properly validate input boundaries and handle overflow conditions. This leads to integer overflow scenarios where computational values exceed their maximum representable limits, causing unpredictable behavior. The vulnerability can be exploited through XML documents that contain specially constructed xsl:number elements with malformed or excessively large numeric parameters.
From an operational perspective, this vulnerability enables remote attackers to execute denial of service attacks against systems running affected software versions. The integer overflow conditions can cause memory corruption, process termination, or excessive resource consumption that degrades system performance. In some configurations, the vulnerability may potentially allow for more severe impacts including arbitrary code execution, though the primary threat remains service disruption. The attack vector requires the victim to process a crafted XML document that utilizes the vulnerable xsl:number formatting, making it particularly concerning for web browsers that process untrusted content.
The security implications of CVE-2016-1684 align with CWE-190, which describes integer overflow vulnerabilities, and can be mapped to ATT&CK technique T1203, representing exploitation of software vulnerabilities for denial of service. The vulnerability demonstrates the importance of proper input validation in XML processing libraries and highlights the risks associated with complex formatting specifications in stylesheet languages. Organizations using affected versions should prioritize patching to prevent exploitation, as the vulnerability can be leveraged without user interaction in web browser contexts. The remediation process requires updating to libxslt 1.1.29 or later versions and ensuring Chrome browsers are updated to 51.0.2704.63 or higher to mitigate the risk of exploitation.