CVE-2025-0899 in PDF-XChange Editor
Summary
by MITRE • 02/11/2025
PDF-XChange Editor AcroForm Use-After-Free Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of PDF-XChange Editor. 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 AcroForms. 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-25349.
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Analysis
by VulDB Data Team • 02/13/2025
This vulnerability resides within PDF-XChange Editor's handling of AcroForm elements, representing a critical use-after-free flaw that enables remote code execution. The vulnerability stems from inadequate input validation mechanisms within the application's form processing subsystem, where the software fails to verify object existence before executing operations on potentially freed memory references. This fundamental flaw allows attackers to manipulate the application's memory management through crafted AcroForm structures, creating conditions where freed memory blocks can be reallocated and accessed improperly. The vulnerability specifically affects versions of PDF-XChange Editor that process interactive form elements, making it particularly dangerous in environments where users frequently interact with PDF documents containing embedded forms.
The technical exploitation of this vulnerability follows a predictable pattern where an attacker crafts a malicious PDF file containing specially constructed AcroForm elements that trigger the use-after-free condition during normal document rendering operations. When the vulnerable application processes such a document, it attempts to access memory that has already been freed, potentially allowing an attacker to control the execution flow through carefully crafted data structures. This memory corruption vulnerability operates at the application level, where the flaw exists in the PDF rendering engine's handling of form field references, and can be leveraged to execute arbitrary code with the privileges of the running process. The vulnerability's classification aligns with CWE-416, which describes use-after-free conditions, and represents a direct threat to application stability and system security.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with persistent access to target systems through remote exploitation. Since user interaction is required for exploitation, attackers typically employ social engineering techniques to deliver malicious PDF files through phishing campaigns or compromised websites. Once successfully exploited, the vulnerability allows attackers to execute malicious code in the context of the PDF-XChange Editor process, potentially leading to complete system compromise. The vulnerability's remote nature makes it particularly attractive to threat actors who can leverage it for widespread attacks without requiring physical access to target systems. This threat vector aligns with ATT&CK technique T1203, which covers exploitation for execution through web-based attacks.
Mitigation strategies for this vulnerability require immediate patching of affected systems, as no effective workarounds exist for the underlying memory management flaw. Organizations should prioritize updating PDF-XChange Editor installations to versions that address the specific use-after-free condition in AcroForm processing, while also implementing network-level controls such as web application firewalls to block malicious PDF content. Security teams should monitor for exploitation attempts through network traffic analysis and endpoint detection systems that can identify anomalous behavior associated with memory corruption exploits. Additionally, user education programs should emphasize the importance of avoiding suspicious PDF files and websites, particularly those containing interactive elements or unexpected form fields. The vulnerability highlights the critical need for robust input validation and memory safety practices in PDF rendering engines, as similar flaws have been identified in other PDF processing applications across the industry.