Less-loader version 2.2.3 introduces several notable updates compared to its predecessor, version 2.2.2, offering developers enhanced compatibility and tooling options for streamlining their webpack-based projects. One significant change lies in the updated development dependencies. Version 2.2.3 upgrades key tools, including less to version ^2.6.1, mocha to ^2.4.5, should to ^8.3.0, webpack to ^1.12.14, css-loader to ^0.23.1, and extract-text-webpack-plugin to ^1.0.1. These upgrades generally incorporate bug fixes, performance improvements, and potentially new features within these individual tools, indirectly benefiting less-loader users.
For developers, these upgrades imply a more stable and feature-rich environment for preprocessing LESS files within webpack workflows. The updated webpack dependency is particularly noteworthy, potentially offering better module bundling and optimization capabilities. Similarly, the refined css-loader enhances CSS handling within the processing pipeline. The older version 2.2.2 relied on older versions of these tools like less at ^2.3.1, mocha at ^2.0.1, should at ^5.2.0, webpack at ^1.1.8, css-loader at ^0.9.1 and extract-text-webpack-plugin at ^0.5.0. Although less peer dependency stay the same, it is important to consider all the other dependency changes to consider upgrading to version 2.2.3. These updated versions enhance a seamless integration with modern webpack configurations.
All the vulnerabilities related to the version 2.2.3 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...');
}