CVE-2025-56589 in HTML2PDF SDK
Summary
by MITRE • 01/22/2026
A Local File Inclusion (LFI) and a Server-Side Request Forgery (SSRF) vulnerability was found in the InsertFromHtmlString() function of the Apryse HTML2PDF SDK thru 11.6.0. These vulnerabilities could allow an attacker to read local files on the server or make arbitrary HTTP requests to internal or external services. Both vulnerabilities could lead to the disclosure of sensitive data or potential system takeover.
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Analysis
by VulDB Data Team • 01/22/2026
The CVE-2025-56589 vulnerability represents a critical security flaw in the Apryse HTML2PDF SDK version 11.6.0 and earlier, where the InsertFromHtmlString() function exhibits dangerous behavior that enables attackers to manipulate file inclusion and network requests. This vulnerability manifests through two distinct but related attack vectors that together create a significant risk for systems utilizing this software component. The Local File Inclusion aspect allows adversaries to access files stored on the server filesystem that should normally be protected from direct access, while the Server-Side Request Forgery component enables attackers to make unauthorized HTTP requests from the server to internal or external targets, potentially exposing internal network resources.
The technical exploitation of this vulnerability occurs through improper input validation within the InsertFromHtmlString() function, which fails to adequately sanitize user-supplied HTML content before processing it into PDF documents. When an attacker provides malicious HTML input containing file paths or URLs, the function processes these without sufficient validation, leading to the execution of unintended file operations or network requests. This flaw directly maps to CWE-22 for improper limitation of a pathname to a restricted directory and CWE-918 for server-side request forgery, both of which are well-documented weaknesses in web application security. The vulnerability's impact extends beyond simple data leakage as it can be leveraged to escalate privileges and potentially achieve complete system compromise through information gathering and reconnaissance activities.
The operational consequences of this vulnerability are severe for organizations relying on the Apryse HTML2PDF SDK for document processing workflows. Attackers could exploit these weaknesses to access sensitive configuration files, database credentials, application source code, or other confidential information stored on the server. The SSRF component particularly threatens internal network security by potentially exposing internal services that would normally be protected by firewalls or network segmentation. This could lead to lateral movement within the network, allowing attackers to discover and target additional systems that are not directly exposed to the internet. The vulnerability essentially creates a backdoor through which attackers can gather intelligence about the internal infrastructure and potentially establish persistent access.
Organizations should immediately implement mitigation strategies including input validation and sanitization of all HTML content passed to the InsertFromHtmlString() function, as well as network segmentation to limit the potential impact of SSRF attacks. The recommended approach involves implementing strict whitelisting of allowed file paths and URL schemes, disabling unnecessary network access from the processing server, and applying the latest available patches from Apryse when released. Security monitoring should include detection of unusual file access patterns and outbound network requests that could indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1059 for command and scripting interpreter and T1566 for phishing with malicious attachments, as attackers could use these flaws to extract sensitive data or establish footholds within the target environment. The vulnerability also represents a significant concern for compliance requirements, as unauthorized data access could violate regulations such as gdpr, hipaa, or pci dss standards.