CVE-2026-57256 in PDF Editor
Summary
by MITRE • 07/08/2026
When the application opens a PDF and executes JavaScript, it performs abnormal operations on the list box field, and this operation is repeated after the form is reset. During this process, the application failed to adequately verify the validity of the form objects and their internal dictionary pointers, resulting in accessing internal members of invalid or improperly initialized fields. This led to an illegal pointer read, ultimately causing the application to crash.
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Analysis
by VulDB Data Team • 07/08/2026
This vulnerability represents a critical memory safety issue that occurs within PDF processing applications when handling JavaScript execution in form fields. The flaw manifests during the interaction with list box fields where abnormal operations are performed, particularly after form reset operations. The root cause lies in insufficient validation of form object integrity and dictionary pointer consistency, creating conditions where the application attempts to access memory locations belonging to invalid or improperly initialized field structures. This improper memory access pattern constitutes a classic buffer over-read vulnerability that can be exploited to trigger arbitrary code execution or denial of service conditions.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the PDF parser's JavaScript engine. When JavaScript commands are executed on list box fields, the application fails to maintain proper object lifecycle management and validation checks. This deficiency allows maliciously crafted PDF documents to manipulate form field states in ways that bypass normal initialization sequences, leaving internal data structures in inconsistent states. The vulnerability specifically affects the handling of dictionary pointers within form objects, where references to memory locations are not properly validated before dereferencing operations occur.
From an operational impact perspective, this vulnerability presents significant risks to end-user systems and enterprise environments. The application crash resulting from illegal pointer reads can be leveraged for denial of service attacks against critical business applications or user devices. In more sophisticated attack scenarios, the memory corruption patterns associated with such pointer read violations could potentially enable privilege escalation or remote code execution depending on the specific implementation details of the affected software. Security researchers categorize this type of vulnerability under CWE-125: "Out-of-bounds Read" and CWE-476: "NULL Pointer Dereference", both of which represent fundamental memory safety weaknesses.
The exploitation of this vulnerability typically requires crafting a malicious PDF document containing specially constructed JavaScript code that triggers the problematic form field operations during the reset sequence. Attackers can leverage this weakness in targeted campaigns against specific user groups or as part of broader exploitation toolkits. Organizations should consider implementing robust input sanitization measures and restricting PDF processing capabilities to trusted sources only. The ATT&CK framework categorizes this type of vulnerability under T1203: "Exploitation for Client Execution" and potentially T1059: "Command and Scripting Interpreter" when JavaScript execution is involved, highlighting the importance of controlling script execution environments.
Mitigation strategies should focus on implementing comprehensive memory safety checks within PDF processing applications, including enhanced validation of form object states before JavaScript execution. Developers must ensure proper initialization sequences for all form fields and implement robust error handling mechanisms that prevent access to invalid memory locations. Regular security updates and patches addressing this specific vulnerability should be prioritized, while organizations may consider deploying PDF sandboxing solutions to isolate potentially malicious documents. Additionally, network-level controls such as content filtering systems can help prevent the delivery of malicious PDF files to end-user systems, reducing the attack surface for this type of memory corruption vulnerability.