CVE-2018-19872 in Qt
Summary
by MITRE
An issue was discovered in Qt 5.11. A malformed PPM image causes a division by zero and a crash in qppmhandler.cpp.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/03/2023
The vulnerability identified as CVE-2018-19872 represents a critical denial of service condition within the Qt 5.11 framework, specifically affecting the Qt Pixmap Module's handling of Portable Pixmap (PPM) image files. This issue manifests when the Qt library processes malformed PPM image data, leading to a division by zero error that ultimately results in application crashes. The flaw exists within the qppmhandler.cpp source file, which is responsible for parsing and rendering PPM image formats, making it a core component of Qt's image processing capabilities.
The technical root cause of this vulnerability stems from inadequate input validation within the PPM image parser implementation. When processing specially crafted PPM files containing malformed header data, the parser fails to properly validate the dimensions or other critical parameters before performing mathematical operations. This particular division by zero occurs during the image processing pipeline where the system attempts to calculate scaling factors or coordinate transformations based on invalid image metadata, resulting in a runtime exception that terminates the executing application.
From an operational impact perspective, this vulnerability presents significant risks to applications that utilize Qt for image processing or display functionality. Attackers could exploit this weakness by crafting malicious PPM files and delivering them through various attack vectors such as email attachments, web downloads, or file sharing systems. When a vulnerable application processes these malicious files, the resulting crash can lead to complete application termination, potentially causing service disruption or system instability. The vulnerability is particularly concerning in environments where Qt applications handle untrusted image data from external sources without proper sanitization.
The flaw aligns with CWE-369, which categorizes division by zero errors as a fundamental programming vulnerability that can lead to system instability and denial of service conditions. This weakness is further classified under ATT&CK technique T1499.004, representing the exploitation of system resource exhaustion through application crashes, which can be leveraged to perform service disruption attacks. Organizations utilizing Qt 5.11 in production environments face potential operational risks including application downtime, user experience degradation, and increased incident response overhead when applications encounter malformed PPM files. The vulnerability demonstrates the importance of robust input validation and error handling in multimedia processing libraries.
Mitigation strategies for CVE-2018-19872 primarily involve upgrading to Qt 5.11.1 or later versions where the division by zero issue has been resolved through proper input validation and error handling mechanisms. System administrators should implement comprehensive image file validation protocols that sanitize all incoming image data before processing, including implementing file format detection and content verification procedures. Additionally, deploying network-based intrusion prevention systems that can identify and block suspicious image file patterns may provide additional layers of protection. Organizations should also consider implementing application sandboxing techniques to limit the impact of potential exploitation attempts and establish monitoring procedures to detect unusual application crash patterns that may indicate exploitation attempts.