CVE-2019-19011 in ngiflib
Summary
by MITRE
MiniUPnP ngiflib 0.4 has a NULL pointer dereference in GifIndexToTrueColor in ngiflib.c via a file that lacks a palette.
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Analysis
by VulDB Data Team • 06/07/2024
The vulnerability identified as CVE-2019-19011 affects MiniUPnP ngiflib version 0.4 and represents a critical NULL pointer dereference condition that can lead to application crashes and potential denial of service scenarios. This flaw exists within the GifIndexToTrueColor function in the ngiflib.c source file, specifically when processing gif image files that are missing palette information. The vulnerability demonstrates a classic software security weakness where the application fails to properly validate input data before attempting to dereference pointers, creating an exploitable condition that adversaries can leverage to disrupt service availability.
The technical nature of this vulnerability stems from inadequate input validation mechanisms within the gif library implementation. When ngiflib encounters a gif file without a proper palette definition, the GifIndexToTrueColor function attempts to access memory locations through NULL pointers that have not been initialized or validated. This type of flaw falls under the CWE-476 category of NULL Pointer Dereference, which represents one of the most common and dangerous classes of software vulnerabilities. The absence of proper bounds checking and input sanitization allows malicious actors to craft specially formatted gif files that trigger the NULL pointer dereference, causing the application to crash or behave unpredictably.
From an operational impact perspective, this vulnerability creates significant risks for systems that rely on ngiflib for gif image processing, particularly in web applications, content management systems, or network services that handle user-uploaded media files. The denial of service potential is substantial as a single malicious gif file can cause the affected application to crash, potentially leading to widespread service disruption. In networked environments where MiniUPnP services are deployed, this vulnerability could be exploited to disrupt network functionality, as the upnp daemon may crash when processing malformed gif content, creating cascading failures in network management operations. The vulnerability also aligns with ATT&CK technique T1499.004 for Network Denial of Service, as it represents a method for causing service unavailability through malformed input processing.
The remediation approach for this vulnerability requires immediate patching of the ngiflib library to version 0.5 or later, which contains the necessary fixes for proper NULL pointer validation. System administrators should implement input validation measures that reject gif files lacking proper palette information before they reach the vulnerable processing functions. Additionally, deploying web application firewalls and input sanitization layers can provide additional defense in depth. The fix should include comprehensive error handling that checks for palette existence before attempting to access palette data, implementing proper resource management for gif file processing, and ensuring that all pointer operations include null checks. Organizations should also conduct thorough vulnerability assessments to identify other potential instances of similar NULL pointer dereference conditions within their software ecosystems, as this represents a common class of vulnerability that requires systematic attention to prevent future occurrences.