Cssnano evolved from version 2.6.1 to 3.0.0 incorporating significant upgrades beneficial for developers seeking efficient CSS minification. Both versions share the core goal of modular CSS minification built upon the PostCSS ecosystem and are licensed under MIT license, ensuring developer freedom. The key difference lies in the underlying PostCSS version with version 3.0.0 upgrading to PostCSS 5.x from prior version's PostCSS 4.x. This shift enables Cssnano to leverage the latest PostCSS features and improvements in parsing and AST manipulation.
Developers will notice updated dependencies showcasing the modular approach of the library, with several PostCSS plugins receiving major version bumps. Version 3.0.0 incorporates newer versions of key plugins like autoprefixer, postcss-colormin, postcss-merge-rules, and postcss-normalize-url, among others. These updates often bring better compression rates, improved handling of CSS syntax and greater overall optimization. Plugins like postcss-svgo are introduced which were not present in prior versions which will provide further image optimization capabilities. The dependency updates signify a clear enhancement in Cssnano's ability to handle modern CSS specifications and offer finer-grained control over the minification process. Notably, some utilities like read-file-stdin and write-file-stdout are removed from the dependencies with the newer version, suggesting a refactoring of internal input/output mechanisms. For developers, this translates to a more efficient, robust, and feature-rich CSS minification experience with cssnano.
All the vulnerabilities related to the version 3.0.0 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");
}
}
}
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.
Denial of Service in js-yaml
Versions of js-yaml prior to 3.13.0 are vulnerable to Denial of Service. By parsing a carefully-crafted YAML file, the node process stalls and may exhaust system resources leading to a Denial of Service.
Upgrade to version 3.13.0.
Code Injection in js-yaml
Versions of js-yaml prior to 3.13.1 are vulnerable to Code Injection. The load() function may execute arbitrary code injected through a malicious YAML file. Objects that have toString as key, JavaScript code as value and are used as explicit mapping keys allow attackers to execute the supplied code through the load() function. The safeLoad() function is unaffected.
An example payload is
{ toString: !<tag:yaml.org,2002:js/function> 'function (){return Date.now()}' } : 1
which returns the object
{
"1553107949161": 1
}
Upgrade to version 3.13.1.
Regular Expression Denial of Service (ReDoS)
The is-svg package 2.1.0 through 4.2.1 for Node.js uses a regular expression that is vulnerable to Regular Expression Denial of Service (ReDoS). If an attacker provides a malicious string, is-svg will get stuck processing the input.
ReDOS in IS-SVG
A vulnerability was discovered in IS-SVG version 4.3.1 and below where a Regular Expression Denial of Service (ReDOS) occurs if the application is provided and checks a crafted invalid SVG string.
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.