CVE-2018-3774 in url-parse
Summary
by MITRE
Incorrect parsing in url-parse <1.4.3 returns wrong hostname which leads to multiple vulnerabilities such as SSRF, Open Redirect, Bypass Authentication Protocol.
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Analysis
by VulDB Data Team • 05/01/2023
The vulnerability identified as CVE-2018-3774 resides within the url-parse library version 1.4.2 and earlier, where improper handling of certain URL formats results in incorrect hostname extraction during parsing operations. This fundamental parsing flaw creates a cascade of security implications that extend far beyond simple URL interpretation errors. The vulnerability specifically affects applications that rely on url-parse for URL validation, redirection handling, or protocol enforcement mechanisms, making it a critical concern for web applications and services that process user-supplied URLs.
The technical root cause of this vulnerability stems from the library's inability to properly handle edge cases in URL formatting, particularly when dealing with malformed or specially crafted URLs that contain unusual hostname patterns. When the url-parse library encounters such inputs, it incorrectly extracts or interprets the hostname component, leading to scenarios where the parsed URL does not accurately represent the intended destination. This parsing error manifests in several distinct ways including the misinterpretation of protocol schemes, incorrect handling of special characters, and improper normalization of hostname values that can result in unexpected behavior during URL processing.
The operational impact of CVE-2018-3774 is particularly severe as it enables multiple attack vectors that can be exploited by malicious actors. Server-Side Request Forgery attacks become possible when applications use the incorrectly parsed hostname to construct requests to internal services or external endpoints, potentially allowing attackers to bypass network restrictions and access protected resources. Open redirect vulnerabilities emerge when the flawed hostname parsing causes applications to redirect users to unintended destinations, enabling phishing attacks or malicious link manipulation. Authentication bypass scenarios can also occur when protocol enforcement mechanisms fail due to incorrect hostname interpretation, allowing attackers to manipulate authentication flows or session management.
From a cybersecurity perspective, this vulnerability aligns with several common weakness enumerations including CWE-20 Improper Input Validation and CWE-601 URL Redirection to Untrusted Site. The attack patterns associated with this vulnerability map directly to ATT&CK techniques such as T1071.004 Application Layer Protocol DNS and T1566 Phishing, as attackers can leverage the incorrect hostname parsing to manipulate URL redirections and deceive users. The vulnerability also relates to T1190 Exploitation of Remote Services when it enables unauthorized access to internal systems through server-side request forgery attacks.
Mitigation strategies for CVE-2018-3774 require immediate remediation through library version updates to 1.4.3 or later, where the parsing logic has been corrected to properly handle edge cases and malformed URL inputs. Organizations should implement comprehensive input validation measures that include additional URL sanitization checks beyond the library's built-in parsing capabilities, ensuring that all URL processing operations include redundant validation layers. Security teams should conduct thorough code reviews to identify all instances where url-parse or similar URL parsing libraries are used, particularly in authentication flows, redirect handlers, and outbound request mechanisms. Additionally, implementing network-level controls such as firewall rules and proxy configurations that can detect and block suspicious URL patterns can provide defense-in-depth protection against exploitation attempts.
The broader implications of this vulnerability highlight the critical importance of proper URL parsing and validation in modern web applications. Given that many applications depend on third-party libraries for URL processing, this vulnerability demonstrates how seemingly minor parsing errors can have cascading security consequences. Organizations should establish robust dependency management practices that include regular security assessments of third-party libraries and maintain up-to-date vulnerability monitoring systems to quickly identify and remediate similar issues across their software ecosystems. The incident also underscores the necessity of implementing automated testing procedures that specifically target URL parsing edge cases to prevent similar vulnerabilities from being introduced into production systems.