CVE-2021-38567 in Foxit
Summary
by MITRE • 08/12/2021
An issue was discovered in Foxit PDF Editor before 11.0.1 and PDF Reader before 11.0.1 on macOS. It mishandles missing dictionary entries, leading to a NULL pointer dereference, aka CNVD-C-2021-95204.
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Analysis
by VulDB Data Team • 08/16/2021
The vulnerability identified as CVE-2021-38567 represents a critical memory safety issue affecting Foxit PDF Editor and PDF Reader versions prior to 11.0.1 on macOS platforms. This flaw manifests as an improper handling of missing dictionary entries within PDF document structures, creating a condition where the application fails to properly validate dictionary elements before attempting to access them. The issue stems from inadequate input validation mechanisms that do not sufficiently check for the presence of required dictionary entries before dereferencing pointers to these elements. Such deficiencies in defensive programming practices create exploitable conditions that can lead to application instability and potential system compromise.
The technical implementation of this vulnerability demonstrates a classic null pointer dereference scenario where the PDF processing engine encounters a dictionary structure that lacks expected key-value pairs. When the application attempts to access memory locations associated with these missing entries without proper null checks, it results in a segmentation fault or crash. This behavior aligns with CWE-476, which specifically addresses null pointer dereference conditions in software systems. The vulnerability is particularly concerning in the context of macOS environments where PDF processing applications are frequently used for document review and collaboration, making them attractive targets for exploitation.
The operational impact of this vulnerability extends beyond simple application crashes to potentially enable more sophisticated attack vectors. When a PDF document is processed by the affected Foxit applications, an attacker could craft malicious PDF files containing malformed dictionary structures designed to trigger this null pointer dereference. The resulting application instability could be leveraged to cause denial of service conditions or potentially provide a foothold for further exploitation. This vulnerability affects the core functionality of PDF processing, which is fundamental to how users interact with documents in professional and enterprise environments, making the impact widespread and significant.
Mitigation strategies for this vulnerability require immediate patch deployment to update Foxit applications to versions 11.0.1 or later where the dictionary handling logic has been corrected. Organizations should implement comprehensive software update policies to ensure all endpoints running Foxit PDF applications receive these security patches promptly. Additionally, network administrators should consider implementing PDF scanning and validation procedures as part of their security infrastructure to detect and block potentially malicious PDF files before they reach end users. The vulnerability also highlights the importance of proper defensive programming practices including input validation, null pointer checking, and robust error handling mechanisms that align with security best practices recommended by organizations such as the Open Web Application Security Project. This issue demonstrates the critical need for continuous security testing and validation of document processing libraries to prevent similar memory safety issues from compromising user systems.