Description
The package koa-remove-trailing-slashes before 2.0.2 are vulnerable to Open Redirect via the use of trailing double slashes in the URL when accessing the vulnerable endpoint (such as https://example.com//attacker.example/). The vulnerable code is in index.js::removeTrailingSlashes(), as the web server uses relative URLs instead of absolute URLs.
Remediation
References
https://github.com/vgno/koa-remove-trailing-slashes/blame/6a01ba8fd019bd3ece44879c553037ad96ba7d47/index.js%23L31
https://snyk.io/vuln/SNYK-JS-KOAREMOVETRAILINGSLASHES-1085708