CVE-2026-18116 Details
Concrete CMS 8.3.0 to 9.5.2 stored calendar event names without sanitization and rendered them without HTML escaping in the workflow approval and deletion notifications shown in the dashboard "Waiting For Me" block. A registered user permitted to add events to a calendar governed by an approval workflow could submit an event whose name contained a script payload, which then executed in an administrator's browser when the pending request was displayed and could be used to create a new administrator account. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks v01demort for reporting.
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Exploit prediction scoring system (EPSS) score for CVE-2026-18116
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%).
0.26 Probability of exploitation activity being observed over the next 30 days (17th percentile)
CVSS score for CVE-2026-18116
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-2026-18116
ConcreteCMS 8.3.0
ConcreteCMS 8.3.1
ConcreteCMS 8.3.2
ConcreteCMS 8.4.0
ConcreteCMS 8.4.1
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-2026-18116 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 2,059 35.37%
DE 922 15.84%
JP 613 10.53%
GB 519 8.92%
NL 319 5.48%
CA 316 5.43%
FR 155 2.66%
CH 125 2.15%
PL 100 1.72%
FI 88 1.51%

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CVE-2026-18116 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 4,803 89.39%
Telecommunications 414 7.71%
Education 55 1.02%
Business Services 51 0.95%
Government/Politics 12 0.22%
Media/Entertainment 10 0.19%
Healthcare/Wellness 8 0.15%
Transportation 7 0.13%
Manufacturing 5 0.09%
Finance 4 0.07%

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