Open Redirect Affecting koa-remove-trailing-slashes package, versions <2.0.2


0.0
medium

Snyk CVSS

    Exploit Maturity Proof of concept
    Attack Complexity Low
    User Interaction Required
Expand this section
NVD
5.4 medium

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  • Snyk ID SNYK-JS-KOAREMOVETRAILINGSLASHES-1085708
  • published 17 May 2021
  • disclosed 15 Mar 2021
  • credit apple502j

How to fix?

Upgrade koa-remove-trailing-slashes to version 2.0.2 or higher.

Overview

koa-remove-trailing-slashes is a Koa middleware that makes sure all requests does not have trailing slashes

Affected versions of this package 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.

PoC

// Run the code below to set up a vulnerable server instance
// Then access http://localhost:3000///example.com

const Koa = require('koa'); const removeTrailingSlashes = require('koa-remove-trailing-slashes');

const app = new Koa();

app.use(removeTrailingSlashes());

app.use(ctx => { ctx.body = 'Hello World'; });

app.listen(3000);

References