CVE-2020-7740 in node-pdf-generator
Summary
by MITRE • 10/06/2020
This affects all versions of package node-pdf-generator. Due to lack of user input validation and sanitization done to the content given to node-pdf-generator, it is possible for an attacker to craft a url that will be passed to an external server allowing an SSRF attack.
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Analysis
by VulDB Data Team • 11/17/2020
The vulnerability identified as CVE-2020-7740 resides within the node-pdf-generator package, a widely used Node.js library for generating PDF documents from HTML content. This security flaw represents a critical server-side request forgery vulnerability that stems from inadequate input validation and sanitization mechanisms. The package fails to properly validate user-provided URLs before processing them, creating an exploitable pathway for malicious actors to manipulate the application's behavior. The vulnerability affects all versions of the package, indicating a fundamental design flaw that has persisted across multiple releases and likely impacted numerous applications relying on this library for PDF generation capabilities.
The technical implementation of this vulnerability occurs when the node-pdf-generator library accepts user input containing URLs that are then forwarded to external servers without proper validation. Attackers can craft malicious URLs that exploit the library's trust in user-provided data, potentially enabling them to make requests to internal network services that should remain isolated from external access. This flaw operates at the intersection of input validation failure and improper trust assumptions in the application's request handling mechanisms. The vulnerability allows attackers to bypass normal network restrictions and potentially access internal resources that would otherwise be protected by firewalls or network segmentation.
The operational impact of this vulnerability extends beyond simple data exposure, as it can enable attackers to perform reconnaissance activities within internal networks, potentially leading to further exploitation opportunities. An attacker could leverage this vulnerability to probe internal services, access sensitive data, or even establish persistence within the target environment. The SSRF attack vector created by this vulnerability aligns with common attack patterns documented in the ATT&CK framework under the "Server-Side Request Forgery" technique, where adversaries manipulate applications into making unintended requests to internal or external systems. This vulnerability particularly affects applications that process user-generated content or allow external URL inputs for PDF generation purposes, making it a significant concern for web applications handling document processing.
Mitigation strategies for CVE-2020-7740 should focus on implementing strict input validation and sanitization for all URL parameters passed to the node-pdf-generator library. Organizations should consider updating to patched versions of the package if available, or implementing additional layers of validation at the application level to ensure that only trusted URLs are processed. The vulnerability demonstrates the importance of proper input validation practices as outlined in CWE-20, which addresses "Improper Input Validation" and is commonly associated with SSRF vulnerabilities. Security teams should also implement network segmentation and access controls to limit the potential impact of successful SSRF attacks, while monitoring for unusual outbound network requests that might indicate exploitation attempts. The remediation process should include thorough code reviews to identify similar patterns in other libraries or application components that might be susceptible to the same class of vulnerability.