The package css-what before 2.1.3 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the usage of insecure regular expression in the re_attr variable of index.js. The exploitation of this vulnerability could be triggered via the parse function.
https://security.snyk.io/vuln/SNYK-JS-CSSWHAT-3035488
https://lists.debian.org/debian-lts-announce/2023/03/msg00001.html
https://github.com/fb55/css-what/blob/a38effd5a8f5506d75c7f8f13cbd8c76248a3860/index.js%23L12