CVE-2026-73646
High
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. Prior to 8.5.18, lib/previous-map.js loadMap() passes attacker-controlled sourceMappingURL values to join(dirname(opts.from), annotation), and loadFile() permits traversed or absolute .map paths, allowing untrusted CSS processed without map: false to disclose sourcesContent from arbitrary reachable .map files through result.map. This issue is fixed in version 8.5.18.
SeverityHigh
CVSS7.5
Exploit probability—
ProductPostcss
PublishedAug 17, 2026
First seenAug 17, 2026
Weakness typeCWE-22Path traversal
How to fix
Update
- postcss8.5.18 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| postcssnpm | v < 8.5.18 | 8.5.18 |
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