Impact Default file permissions for log files created by the file, fileSync and dateFile appenders are world-readable (in unix). This could cause problems if log files contain sensitive information. This would affect any users that have not supplied their own permissions for the files via the mode parameter in the config. Patches Fixed by: https://github.com/log4js-node/log4js-node/pull/1141 https://github.com/log4js-node/streamroller/pull/87 Released to NPM in log4js@6.4.0 Workarounds Every version of log4js published allows passing the mode parameter to the configuration of file appenders, see the documentation for details. References Thanks to ranjit-git for raising the issue, and to @lamweili for fixing the problem. For more information If you have any questions or comments about this advisory: Open an issue in logj4s-node Ask a question in the slack channel Email us at gareth.nomiddlename@gmail.com