Denial of Service in Nodemailer SMTP Client

Executive Summary

Nodemailer versions from 3.0.0 to 10.0.10 have a denial of service vulnerability due to quadratic complexity in the SMTP client reply parser. A malicious SMTP server or attacker can send continuation lines without a completion line before authentication, blocking the Node.js event loop and exhausting memory.

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Detection Guidance

To detect this vulnerability, monitor for unusual SMTP traffic patterns or memory exhaustion in Node.js applications using Nodemailer versions before 10.0.10. Check for long-running SMTP connections with excessive partial responses. Use tools like netstat or ss to inspect SMTP connections and Node.js process memory usage with commands like 'top' or 'htop'.

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Impact Analysis

This vulnerability can cause your application to hang or crash by consuming excessive memory and CPU resources. It disrupts normal operations by blocking the Node.js event loop, potentially leading to downtime or degraded performance for services relying on Nodemailer.

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Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling denial of service attacks that disrupt service availability. GDPR requires data processing systems to maintain availability, and HIPAA mandates access to protected health information. Exploits could block event loops and exhaust memory, leading to service disruptions.

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Mitigation Strategies

Upgrade Nodemailer to version 10.0.10 or later to address the quadratic complexity denial of service vulnerability in the SMTP client reply parser.

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