Node.js vulnerabilities directly affect Express. Therefore keep a watch on Node.js vulnerabilities and make sure you are using the latest stable version of Node.js.
The list below enumerates the Express vulnerabilities that were fixed in the specified version update.
NOTE: If you believe you have discovered a security vulnerability in Express, please see Security Policies and Procedures.
forwarded has been updated to address a vulnerability. This may affect your application if the following APIs are used: req.host, req.hostname, req.ip, req.ips, req.protocol.mime has been updated to address a vulnerability, but this issue does not impact Express.send has been updated to provide a protection against a Node.js 8.5.0 vulnerability. This only impacts running Express on the specific Node.js version 8.5.0.debug has been updated to address a vulnerability, but this issue does not impact Express.fresh has been updated to address a vulnerability. This will affect your application if the following APIs are used: express.static, req.fresh, res.json, res.jsonp, res.send, res.sendfile res.sendFile, res.sendStatus.ms has been updated to address a vulnerability. This may affect your application if untrusted string input is passed to the maxAge option in the following APIs: express.static, res.sendfile, and res.sendFile.qs has been updated to address a vulnerability, but this issue does not impact Express. Updating to 4.15.2 is a good practice, but not required to address the vulnerability.express.static, res.sendfile, and res.sendFileexpress.static (advisory, CVE-2015-1164).express.static (advisory , CVE-2014-6394).fds in certain situations that affect express.static and res.sendfile. Malicious requests could cause fds to leak and eventually lead to EMFILE errors and server unresponsiveness.Express 3.x IS NO LONGER MAINTAINED
Known and unknown security issues in 3.x have not been addressed since the last update (1 August, 2015). Using the 3.x line should not be considered secure.
express.static, res.sendfile, and res.sendFileexpress.static (advisory, CVE-2015-1164).express.static.fds in certain situations that affect express.static and res.sendfile. Malicious requests could cause fds to leak and eventually lead to EMFILE errors and server unresponsiveness.