CVE-2019-18804 in DjVuLibre
Summary
by MITRE
DjVuLibre 3.5.27 has a NULL pointer dereference in the function DJVU::filter_fv at IW44EncodeCodec.cpp.
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Analysis
by VulDB Data Team • 02/05/2024
The vulnerability identified as CVE-2019-18804 resides within DjVuLibre version 3.5.27, a widely used open-source library for handling DjVu document format processing. This particular flaw manifests as a NULL pointer dereference within the DJVU::filter_fv function located in the IW44EncodeCodec.cpp source file, representing a critical software reliability issue that can potentially lead to application instability and denial of service conditions. The vulnerability demonstrates characteristics consistent with CWE-476 which specifically addresses NULL pointer dereferences, making it a well-documented weakness in software security practices.
The technical implementation of this vulnerability occurs when the DJVU::filter_fv function attempts to access memory through a pointer that has not been properly initialized or validated. This NULL pointer dereference represents a fundamental flaw in the program's memory management and input validation mechanisms. The function operates within the context of image processing for DjVu documents, specifically handling frequency domain filtering operations during the IW44 encoding process. When malformed or unexpected input data is processed, the function fails to properly check for NULL pointer conditions before attempting memory access, leading to a crash of the application process.
The operational impact of this vulnerability extends beyond simple application crashes, as it creates a potential denial of service condition that can be exploited by malicious actors. When an attacker crafts specific DjVu files containing malformed data structures, they can trigger the NULL pointer dereference and cause the target application to terminate unexpectedly. This behavior aligns with ATT&CK technique T1499.004 which covers network denial of service attacks through resource exhaustion or application crashes. The vulnerability affects any software that relies on DjVuLibre 3.5.27 for document processing, including web applications, desktop software, and server-based document handling systems.
Mitigation strategies for this vulnerability primarily focus on immediate software updates and patches to address the root cause within the DjVuLibre library. Organizations should prioritize upgrading to versions of DjVuLibre that have been verified to contain fixes for this NULL pointer dereference issue. Additionally, implementing proper input validation and error handling within applications that utilize this library can provide defensive measures against exploitation attempts. The fix typically involves adding null pointer checks before memory access operations within the affected function, ensuring that all pointers are properly validated before use. Security monitoring should also be implemented to detect unusual patterns of application crashes or service interruptions that might indicate exploitation attempts. System administrators should consider implementing sandboxing techniques and input sanitization for DjVu document processing to minimize potential impact from unpatched systems.