CVE-2026-18111 Details
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.
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Exploit prediction scoring system (EPSS) score for CVE-2026-18111
EPSS (Exploit Prediction Scoring System): EPSS predicts the likelihood that a vulnerability will be exploited in the wild. A higher percentage means a greater chance of an exploit occurring. The EPSS model produces a probability score between 0 and 1 (0 and 100%).
0.19 Probability of exploitation activity being observed over the next 30 days (9th percentile)
CVSS score for CVE-2026-18111
CVSS (Common Vulnerability Scoring System): An open framework owned and managed by FIRST.Org, Inc. that assigns a numerical score from 0 to 10 to software vulnerabilities to indicate their severity.
6.1 Medium
Products affected by CVE-2026-18111
ConcreteCMS 5.7.5.1
ConcreteCMS 5.7.5.10
ConcreteCMS 5.7.5.11
ConcreteCMS 5.7.5.12
ConcreteCMS 5.7.5.13
DVE Score by Bitsight AI
DVE scores complement traditional static scoring systems like CVSS with Bitsight AI powered real-time threat intelligence and underground cyber criminal activity so that security teams can reduce alert fatigue and focus on vulnerabilities most likely to be exploited.
Low
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CVE-2026-18111 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 3,305 34.21%
JP 1,376 14.24%
DE 1,223 12.66%
GB 946 9.79%
NL 397 4.11%
CA 337 3.49%
CH 256 2.65%
FR 251 2.60%
AU 222 2.30%
PL 175 1.81%

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CVE-2026-18111 Industry Footprint

Top 10 Identified Industries

*Service provider organizations (typically Technology and Telecommunications) are disproportionally represented in the results given their upstream ownership of end-user infrastructure. See our FAQs.

Industry* Observations Percentage
Technology 7,256 86.34%
Telecommunications 910 10.83%
Education 104 1.24%
Business Services 53 0.63%
Government/Politics 14 0.17%
Finance 11 0.13%
Energy/Resources 10 0.12%
Manufacturing 10 0.12%
Media/Entertainment 9 0.11%
Transportation 8 0.10%

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