Affected versions of fsk-server resolve relative file paths, resulting in a directory traversal vulnerability. A malicious actor can use this vulnerability to access files outside of the intended directory root, which may result in the disclosure of private files on the vulnerable system.

Example request:

GET /../../../../../../../../../../etc/passwd HTTP/1.1
host:foo

Recommendation

No patch is available for this vulnerability.

It is recommended that the package is only used for local development, and if the functionality is needed for production, a different package is used instead.

References

• https://github.com/JacksonGL/NPM-Vuln-PoC/tree/master/directory-traversal/fsk-server
• https://www.npmjs.com/advisories/345
• https://nvd.nist.gov/vuln/detail/CVE-2017-16090