CVE-2018-17332 in libsvg2
Summary
by MITRE
An issue was discovered in libsvg2 through 2012-10-19. The svgGetNextPathField function in svg_string.c returns its input pointer in certain circumstances, which might result in a memory leak caused by wasteful malloc calls.
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Analysis
by VulDB Data Team • 03/26/2020
The vulnerability identified as CVE-2018-17332 resides within the libsvg2 library, a widely used software component for parsing and rendering svg vector graphics files. This library has been integral to numerous applications and systems that process svg content, making the discovery of memory management flaws particularly concerning for system security and stability. The affected version range indicates this issue existed in the library up to the specific date of October 19, 2012, suggesting that systems running outdated versions of this library remain at risk of exploitation. The vulnerability manifests in the svgGetNextPathField function located within the svg_string.c source file, which serves as a critical parsing routine for extracting path data from svg markup.
The technical flaw within the svgGetNextPathField function represents a memory management error that occurs during the parsing of svg path data elements. When processing certain malformed or edge-case svg input, the function fails to properly handle pointer arithmetic and memory allocation logic, causing it to return an input pointer that has already been processed or freed. This behavior creates a scenario where the library performs unnecessary malloc calls while simultaneously maintaining references to previously allocated memory regions, leading to a memory leak condition. The issue stems from improper state management within the parsing loop, where the function's return logic does not account for all possible execution paths, particularly those involving malformed input sequences that trigger the problematic code path.
The operational impact of this vulnerability extends beyond simple memory consumption issues, as memory leaks in parsing libraries can create significant system stability concerns and potential denial of service conditions. When applications repeatedly process svg content through the vulnerable libsvg2 library, the accumulated memory leaks can gradually consume available system resources, potentially leading to application crashes or system instability. The vulnerability is particularly concerning for web applications and servers that process user-uploaded svg files, as malicious actors could craft specially designed svg files to trigger the memory leak condition repeatedly, resulting in resource exhaustion and service disruption. This type of vulnerability falls under the CWE-401 category of CWE-401: Improper Release of Memory Before Removing Last Reference, which specifically addresses memory management flaws that can lead to resource exhaustion.
From a threat modeling perspective, this vulnerability aligns with the ATT&CK framework's T1499.004 technique related to network denial of service, as the memory leak can be exploited to consume system resources and potentially cause service unavailability. The vulnerability also demonstrates characteristics of T1595.001 technique for reconnaissance activities, as attackers may analyze the behavior of parsing libraries to identify memory management flaws that could be leveraged for more sophisticated attacks. Organizations using affected versions of libsvg2 should prioritize patching or upgrading their implementations to prevent exploitation. The recommended mitigation strategy involves updating to the latest stable version of libsvg2 that contains proper memory management fixes, implementing input validation for svg content, and monitoring system resource consumption for signs of memory leak exploitation. Additionally, security teams should consider implementing sandboxing mechanisms for svg processing and conducting regular vulnerability assessments of their svg-dependent applications to ensure comprehensive protection against similar memory management flaws.