CVE-2026-18111
Concrete CMS 9 before 9.5.3 was vulnerable to stored cross-site scripting (XSS) in the Feature, Feature Link, Hero Image, and Image blocks a…
Concrete CMS 9 before 9.5.3 was vulnerable to stored cross-site scripting (XSS) in the Feature, Feature Link, Hero Image, and Image blocks and before Concrete 8.5.21 in the feature and Image blocks because the external link URL was insufficiently validated by the link filter and was rendered without output escaping. A user with page-editing permissions (such as Add Block combined with Edit Contents on a single page) could store a crafted external link value that broke out of the link markup and injected arbitrary JavaScript. The script executed in the browser session of any user who subsequently viewed, previewed, or edited the affected page, which could lead to session hijacking and escalation of privileges up to full administrative takeover. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 8.5 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks to KhanMarshai for reporting this issue.
Why it matters
- ▸ CVSS vector data not available for this CVE
Apply the vendor patch as soon as it's available or already released.
This analysis is generated from structured CVSS vector data, CISA KEV cross-referencing, and vendor/product category rules — not a manual expert review. Treat it as a starting point, not a substitute for your own assessment.
CVSS Vector Breakdown
No CVSS vector data available for this CVE.
EU Vulnerability Database (ENISA)
EUVD is ENISA's EU vulnerability database, still in beta. EPSS is a probabilistic exploitation-likelihood score, not a certainty.
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