CVE-2026-57259 in PDF Editor
Summary
by MITRE • 07/08/2026
The input file does not need to be strictly in a structurally valid PDF format. Instead, after reviewing the content, the original document disguised as a PDF will be sent to the parser. Malicious documents will construct malicious external entities that, through the protocol, point to local paths, thereby allowing access to any local files within the user's permission range.
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Analysis
by VulDB Data Team • 07/08/2026
This vulnerability represents a critical XML External Entity processing flaw that enables arbitrary file access through malicious document construction. The weakness occurs when parsers accept malformed input containing external entity declarations that reference local file paths, allowing attackers to enumerate system resources and potentially extract sensitive data from the victim's machine. Such vulnerabilities fall under CWE-611 which specifically addresses improper restriction of XML external entities, making them particularly dangerous in environments where XML parsing is prevalent. The attack vector leverages the protocol's ability to resolve references through external entities, creating a path traversal scenario that bypasses normal file system access controls.
The technical implementation involves crafting malicious documents with specially constructed XML entities that reference local paths using protocols such as file:// or http:// schemes. When processed by vulnerable applications, these entities trigger automatic resolution of the referenced paths, enabling attackers to access files within the user's permission scope. This creates a direct pathway for information disclosure attacks where adversaries can extract configuration files, database credentials, system logs, and other sensitive materials from the compromised system. The vulnerability is particularly insidious because it operates at the parsing layer, meaning applications that process XML documents, including web services, content management systems, and document processing tools, may all be affected.
Operational impact of this vulnerability extends beyond simple information disclosure to encompass potential system compromise and data exfiltration. Attackers can leverage the ability to traverse local file systems to discover sensitive files such as ssh keys, database connection strings, application configuration files, and system credentials. The attack chain typically begins with reconnaissance where attackers identify vulnerable applications, followed by crafting malicious payloads that exploit the XML parsing functionality. This vulnerability aligns with ATT&CK technique T1566 which covers spearphishing attachments, specifically targeting the initial access phase through document-based attacks.
Mitigation strategies must address both the immediate parsing vulnerabilities and broader architectural security considerations. Organizations should implement strict XML parser configurations that disable external entity processing entirely or restrict it to trusted sources only. The use of secure XML parsers with proper input validation and sanitization represents a fundamental defensive measure against such attacks. Additionally, network segmentation and privilege separation can limit the damage scope when vulnerabilities are exploited. Regular security assessments of XML processing components, combined with proper access controls and monitoring for unusual file system access patterns, provide layered protection against these threats. Implementation of web application firewalls and input validation mechanisms further reduces attack surface while compliance with standards like OWASP Top 10 helps establish comprehensive security postures against such vulnerabilities.