CVE-2023-39619 in NPMJS Node Email Check
Summary
by MITRE • 10/25/2023
ReDos in NPMJS Node Email Check v.1.0.4 allows an attacker to cause a denial of service via a crafted string to the scpSyntax component.
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Analysis
by VulDB Data Team • 10/05/2025
The vulnerability identified as CVE-2023-39619 represents a Regular Expression Denial of Service (ReDoS) flaw within the Node Email Check package version 1.0.4 distributed through NPMJS. This issue specifically affects the scpSyntax component which processes email address validation logic. The vulnerability stems from the implementation of regular expressions that are susceptible to catastrophic backtracking when processing malformed input strings. Attackers can exploit this weakness by crafting specially designed strings that cause the regular expression engine to consume excessive computational resources, leading to system unresponsiveness or complete service disruption.
The technical implementation of this vulnerability resides in the email validation logic where the scpSyntax function employs regular expressions that exhibit exponential time complexity under certain input conditions. When an attacker provides a maliciously crafted string, the regular expression engine enters into a state of catastrophic backtracking where it repeatedly attempts different matching paths, resulting in exponential execution time growth. This behavior directly violates the principles outlined in CWE-1333 which categorizes improper use of regular expressions as a significant security concern. The vulnerability specifically impacts the input validation mechanisms that are fundamental to email address verification processes, making it particularly dangerous in applications that rely on email validation for user registration, authentication, or data processing workflows.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential system resource exhaustion and application instability. In environments where email validation is frequently performed or where the application processes high volumes of email inputs, an attacker can effectively render the service unusable by submitting malicious input patterns. The vulnerability affects applications that utilize the Node Email Check package, particularly those in web applications, API services, or backend systems that validate email addresses as part of their processing pipeline. This creates a significant risk for systems that do not implement proper input sanitization or rate limiting mechanisms to prevent exploitation of such vulnerabilities.
Mitigation strategies for CVE-2023-39619 should focus on immediate remediation through package updates, as the vulnerability exists within a specific version of the Node Email Check library. Organizations should prioritize updating to the latest available version of the package that addresses the regular expression flaw. Additionally, implementing proper input validation and sanitization measures can provide defense-in-depth protection against similar vulnerabilities. Security practitioners should consider implementing rate limiting and input length restrictions for email validation endpoints to prevent exploitation attempts. The ATT&CK framework categorizes this type of vulnerability under T1499 which encompasses network denial of service attacks, emphasizing the importance of validating input processing and implementing robust error handling mechanisms. Organizations should also conduct comprehensive vulnerability assessments to identify other potential ReDoS vulnerabilities in their dependency tree, as this represents a common pattern in software libraries that process user input through regular expressions.