In all versions of Node.js 10 prior to 10.9.0, an argument processing flaw can cause Buffer.alloc() to return uninitialized memory. This method is intended to be safe and only return initialized, or cleared, memory. The third argument specifying encoding can be passed as a number, this is misinterpreted by Buffer's internal "fill" method as the start to a fill operation. This flaw may be abused where Buffer.alloc() arguments are derived from user input to return uncleared memory blocks that may contain sensitive information.

References

• https://nvd.nist.gov/vuln/detail/CVE-2018-7166
• https://access.redhat.com/errata/RHSA-2018:2553
• https://nodejs.org/en/blog/vulnerability/august-2018-security-releases/