CVE-2026-45623 PostCSS: Arbitrary file read and information disclosure via attacker-controlled sourceMappingURL in CSS comments

🗓️ 27 Jul 2026 17:23:13Reported by GitHub_MType

PostCSS before 8.5.12 allowed arbitrary file read via source mapping URL in CSS comments, leaking initial bytes.

Reporter	Title	Published	Views	Family All 78
IBM Security Bulletins	Security Bulletin: IBM Maximo Application Suite - Cluster Performance Insights uses ansible_core-2.19.11, postcss-8.5.10 and dompurify-3.4.11 which are vulnerable to CVE-2026-16493, CVE-2026-45623, CVE-2026-69153 and CVE-2026-66010	28 Aug 202610:04	–	ibm
IBM Security Bulletins	Security Bulletin: IBM Maximo Application Suite - Monitor Component uses postcss-8.4.38.tgz package which is vulnerable to CVE-2026-45623.	27 Aug 202619:34	–	ibm
IBM Security Bulletins	Security Bulletin: There are vulnerabilities in IBM Maximo Manage application in IBM Maximo Application Suite	28 Aug 202605:57	–	ibm
IBM Security Bulletins	Security Bulletin: IBM Maximo Application Suite uses postcss-8.5.10.tgz which is vulnerable to CVE-2026-45623	1 Sep 202613:54	–	ibm
ATTACKERKB	CVE-2026-45623	27 Jul 202617:23	–	attackerkb
Chainguard	CVE-2026-45623 vulnerabilities	28 Jul 202608:22	–	cgr
Circl	CVE-2026-45623	23 Jul 202616:35	–	circl
Atlassian	Information Disclosure postcss Dependency in Confluence Data Center	5 Aug 202616:31	–	atlassian
Atlassian	Information Disclosure postcss Dependency in Crowd Data Center	1 Aug 202604:31	–	atlassian
CVE	CVE-2026-45623	27 Jul 202617:23	–	cve

[
  {
    "vendor": "postcss",
    "product": "postcss",
    "versions": [
      {
        "version": "< 8.5.12",
        "status": "affected"
      }
    ]
  }
]

Source	Link
github	www.github.com/postcss/postcss/security/advisories/GHSA-6g55-p6wh-862q

27 Jul 2026 17:23Current

CVSS 3.17.5

EPSS0.00587