InstantCMS vulnerable to Server-Side Request Forgery via package installer

Vulnerability Description

InstantCMS is a free and open source content management system. A blind Server-Side Request Forgery (SSRF) vulnerability in InstantCMS up to and including 2.17.3 allows authenticated remote attackers to make nay HTTP/HTTPS request via the package parameter. It is possible to make any HTTP/HTTPS request to any website in installer functionality. Due to such vulnerability it is possible to for example scan local network, call local services and its functions, conduct a DoS attack, and/or disclose a server's real IP if it's behind a reverse proxy. It is also possible to exhaust server resources by sending plethora of such requests. As of time of publication, no patched releases are available.

References

• https://github.com/instantsoft/icms2/security/advisories/GHSA-79hh-mhvg-whrw
• https://github.com/instantsoft/icms2/commit/fa997bdab3429fad0c850966bfacbcb96d5ab041