Description
PostCSS takes a CSS file and provides an API to analyze and modify its rules by transforming the rules into an Abstract Syntax Tree. Versions prior to 8.5.10 do not escape `</style>` sequences when stringifying CSS ASTs. When user-submitted CSS is parsed and re-stringified for embedding in HTML `<style>` tags, `</style>` in CSS values breaks out of the style context, enabling XSS. Version 8.5.10 fixes the issue.
Problem types
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Product status
References
github.com/...ostcss/security/advisories/GHSA-qx2v-qp2m-jg93
github.com/...ostcss/security/advisories/GHSA-qx2v-qp2m-jg93
github.com/postcss/postcss/releases/tag/8.5.10