Log injection vulnerability is a common security issue in JavaScript and Node.js applications where attackers manipulate input data to inject malicious code into logs. This can compromise the integrity and confidentiality of an application. To prevent log injection vulnerabilities, developers should sanitize user inputs, be cautious about what they log, use structured logging, and consider using a logging library like pino. Additionally, tools such as Snyk's IDE extension for Visual Studio Code can help detect potential security issues in code.