CVE-2018-19873 in Qt
Summary
by MITRE
An issue was discovered in Qt before 5.11.3. QBmpHandler has a buffer overflow via BMP data.
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Analysis
by VulDB Data Team • 02/11/2025
The vulnerability identified as CVE-2018-19873 represents a critical buffer overflow flaw within the Qt framework's QBmpHandler component, affecting versions prior to 5.11.3. This issue resides in the handling of bitmap image data and demonstrates how multimedia processing libraries can become attack vectors when proper input validation mechanisms are absent. The vulnerability specifically targets the BMP file format parsing functionality, which is commonly used for image representation across various applications and systems. When Qt processes BMP files through the QBmpHandler, the software fails to properly validate the size parameters of the bitmap data structure, creating opportunities for malicious actors to exploit this weakness.
The technical implementation of this buffer overflow occurs during the parsing of BMP file headers and pixel data where the application reads dimensions and size indicators without adequate bounds checking. This flaw allows attackers to craft malicious BMP files with manipulated header values that specify oversized data structures, causing the application to allocate insufficient memory buffers for image processing operations. When the system attempts to read or write beyond these allocated boundaries, it results in memory corruption that can be leveraged for arbitrary code execution. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of how improper input validation in image processing libraries can lead to severe security implications.
The operational impact of CVE-2018-19873 extends across numerous applications that utilize Qt for graphical user interfaces and image handling capabilities. This includes desktop applications, mobile applications, and embedded systems that rely on Qt's multimedia framework for displaying bitmap images. Attackers could exploit this vulnerability by delivering malicious BMP files through various attack vectors including email attachments, web downloads, or file sharing platforms. The exploitation process typically involves crafting a specially formatted BMP file that triggers the buffer overflow when the victim's application attempts to load or display the image. This vulnerability affects both end-user applications and server-side components that process user-uploaded images, creating potential for remote code execution and system compromise.
Mitigation strategies for this vulnerability require immediate patching of affected Qt installations to version 5.11.3 or later, where the buffer overflow has been resolved through proper input validation and bounds checking mechanisms. Organizations should implement comprehensive application whitelisting policies to restrict execution of untrusted image files, particularly in environments where users can upload content. Network-based protections such as intrusion detection systems should be configured to monitor for suspicious BMP file patterns that might indicate exploitation attempts. Additionally, security teams should conduct thorough vulnerability assessments of all Qt-based applications to identify potential attack surfaces and ensure proper input sanitization practices are implemented throughout the application stack. The remediation process should also include monitoring for any potential exploitation attempts through log analysis and implementing proper error handling that prevents crash-based information disclosure. This vulnerability demonstrates the importance of maintaining up-to-date software libraries and implementing defense-in-depth strategies that protect against memory corruption vulnerabilities across all layers of the application architecture.