CVE-2023-27366 in Foxit
Summary
by MITRE • 05/03/2024
Foxit PDF Reader Doc Object Use-After-Free Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit PDF Reader. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the handling of Doc objects. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-20225.
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Analysis
by VulDB Data Team • 08/13/2025
The CVE-2023-27366 vulnerability represents a critical use-after-free flaw in Foxit PDF Reader that enables remote code execution through malicious PDF documents or web pages. This vulnerability resides within the document object handling mechanism of the PDF reader application, specifically in how the software manages Doc objects during processing. The flaw allows attackers to manipulate the memory state of the application by referencing objects that have already been freed, creating a dangerous condition that can be exploited to gain arbitrary code execution privileges. The vulnerability was previously catalogued as ZDI-CAN-20225, indicating it had been previously identified and analyzed by the Zero Day Initiative security research team. This particular weakness demonstrates a fundamental failure in memory management practices within the PDF rendering engine of Foxit Reader, where proper object lifecycle management is not enforced during document processing operations.
The technical exploitation of this vulnerability occurs when a malicious PDF document or web page containing crafted content is accessed by an unsuspecting user. The flaw manifests during the handling of Doc objects where the application fails to validate whether an object still exists in memory before attempting operations on it. This validation gap creates a window where freed memory can be reused, allowing an attacker to place malicious code in the memory location that was previously occupied by the freed object. When the application subsequently attempts to access this object, it inadvertently executes the attacker-controlled code within the context of the current process, effectively elevating privileges to match those of the PDF reader application. The vulnerability requires user interaction to be successful, meaning that the target must either visit a malicious webpage or open a specifically crafted malicious file, making it a typical remote code execution vector that relies on social engineering tactics to achieve compromise.
The operational impact of this vulnerability extends beyond simple code execution, as it can potentially allow attackers to completely compromise the affected system. Since the exploit operates within the context of the PDF reader process, attackers can leverage this to access sensitive data, install additional malware, or establish persistence mechanisms within the victim's environment. The vulnerability affects all versions of Foxit PDF Reader that are susceptible to this memory management flaw, making it particularly dangerous given the widespread use of this PDF reader software across various organizations and individual users. The use-after-free condition creates a stable exploitation environment where attackers can reliably execute malicious payloads, as the memory layout and object reuse patterns can be predicted and manipulated. This vulnerability directly aligns with CWE-416, which specifically addresses the use of freed memory conditions, and represents a classic example of improper memory management in security-critical applications. The attack surface is significantly broadened by the fact that PDF documents can be delivered through multiple vectors including email attachments, web downloads, and malicious websites, increasing the likelihood of successful exploitation.
Mitigation strategies for CVE-2023-27366 should prioritize immediate patching of affected Foxit PDF Reader installations to address the underlying use-after-free vulnerability. Organizations should implement network-based security controls such as web filtering and email scanning to prevent users from accessing malicious PDF content, particularly when these documents are delivered through untrusted sources. The implementation of application whitelisting and sandboxing techniques can provide additional layers of protection by restricting the execution environment of PDF reader applications and limiting potential damage from successful exploitation attempts. Security monitoring should include detection of unusual PDF processing activities and memory access patterns that may indicate exploitation attempts. Users should be educated about the risks of opening PDF documents from untrusted sources and the importance of keeping their software updated. The vulnerability also highlights the importance of following secure coding practices and conducting regular security assessments of PDF rendering engines to identify similar memory management flaws that could be exploited by threat actors. Given the nature of the vulnerability, which operates at the memory management level of the application, comprehensive testing of patched versions is essential to ensure that the fix properly addresses the object lifecycle validation issues and prevents future exploitation attempts.