Advisories for Npm/Postcss package

The fix for GHSA-6g55-p6wh-862q added a guard in lib/previous-map.js PreviousMap.loadFile() that restricts an attacker-controlled sourceMappingURL (from a CSS comment) to a .map extension and, for untrusted maps, rejects .. traversal and absolute paths. The traversal/absolute rejection is nested inside if (cssFile) { … }. When PostCSS is invoked without the from option, cssFile is falsy and that branch is skipped, leaving only the .map extension check. PreviousMap is constructed by …

Disclosure of the contents of arbitrary .map files reachable via path traversal (or absolute path when from is unset) from the process's filesystem. Affects any application processing CSS it does not fully trust without explicitly passing map: false. No authentication or user interaction beyond submitting CSS text is required.

PostCSS's PreviousMap parses the /*# sourceMappingURL=PATH */ comment from any CSS string passed to process() and dereferences PATH against the local filesystem with no scheme, allowlist, or traversal check. An attacker who controls the CSS input can cause the host process to read any file readable by Node and leak the first ~10 bytes of its content through the resulting JSON.parse SyntaxError message. The bug also yields a precise file-existence …

PostCSS v8.5.5 (latest) does 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.

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 …

The package postcss is vulnerable to Regular Expression Denial of Service (ReDoS) via getAnnotationURL() and loadAnnotation() in lib/previous-map.js.

The package postcss from are vulnerable to Regular Expression Denial of Service (ReDoS) during source map parsing.