This indicates an attack attempt to exploit a Security Bypass Vulnerability in Node.js.
The vulnerability is caused by improper validation of user supplied data when the vulnerable application handles a maliciously crafted request. An attacker can exploit this to execute arbitrary code in the context of the vulnerable application via a crafted request.
Node.js 8.5.0 before 8.6.0
Security Bypass: Remote attackers can bypass security checking of vulnerable systems.
Apply the most recent upgrade or patch from the vendor. Or follow the workaround in below link.