CVE-2026-73646: PostCSS: Path Traversal in Previous Source Map Auto-Loading (sourceMappingURL) leads to Arbitrary .map File Disclosure
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.
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N · CWE-22
Tracked companies
Mapped from the CVE’s affected-product data, NVD CPE matches, vendor advisories or package feeds. A mapping means the vendor’s software is named, not that its hosted service was exposed.
Status incidents that name it
No tracked status incident names this CVE.
Affected vendors and products
postcss: postcss
References
- CVE record on cve.org (opens in new tab)
- NVD entry (opens in new tab)
- github.com/postcss/postcss/commit/95663d3eb7ba26f4854dd19d3b4f4425760cf56c (opens in new tab)
- github.com/postcss/postcss/releases/tag/8.5.18 (opens in new tab)
- github.com/postcss/postcss/security/advisories/GHSA-r28c-9q8g-f849 (opens in new tab)
- CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (opens in new tab)
- This product uses data from the NVD API but is not endorsed or certified by the NVD. (opens in new tab)
- Known Exploited Vulnerabilities catalog from CISA. (opens in new tab)
- EPSS scores from FIRST (Exploit Prediction Scoring System). (opens in new tab)