Insertion of Sensitive Information into Log File
A sensitive data disclosure flaw was found in the way Logstash versions before 5.6.15 and 6.6.1 logs malformed URLs. If a malformed URL is specified as part of the Logstash configuration, the credentials for the URL could be inadvertently logged as part of the error message.
CWE-532 - Insertion of Sensitive Information into Log File
It's quite common for applications to save logs. For example, whenever a user requests a resource from a particular website, the web server writes information about the request to a log file. These files are helpful for identifying abnormal system activity, bugs, and evaluating the security controls of the application. Security of log files is critical for the overall security of the application and its confidential resources. An application that lacks appropriate logging levels can expose sensitive user data and system information stored on the log files to malicious users. This info can be exploited to compromise your system.