CVE-2026-18110 Details
Concrete CMS 9 (9.0.0 through 9.5.2) does not perform an authorization check on the user selector autocomplete endpoint (/ccm/system/user/autocomplete), which backs the "Preview as User" panel and other user-selector components. The endpoint validates only a CSRF-style access token that is bound to the selector's display options rather than to the caller's identity or permissions, and that token is issued to anonymous visitors because the selector renders without an authorization check. Because an empty query resolves to a match-all filter, an unauthenticated attacker can submit an empty search and paginate the results to enumerate every backend account, disclosing the internal user ID, username, and email address of all administrative users, including the super-administrator (user ID 1). No password hashes or session material are disclosed The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 8.7 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks thirtythree and YesWeHack for reporting.
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Exploit prediction scoring system (EPSS) score for CVE-2026-18110
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%).
1.59 Probability of exploitation activity being observed over the next 30 days (76th percentile)
CVSS score for CVE-2026-18110
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.
7.5 High
Products affected by CVE-2026-18110
ConcreteCMS 9.5.1
ConcreteCMS 9.5.2
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-2026-18110 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 506 56.41%
DE 114 12.71%
JP 92 10.26%
NL 37 4.12%
GB 37 4.12%
AU 18 2.01%
DK 16 1.78%
CH 12 1.34%
FR 10 1.11%
CA 10 1.11%

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CVE-2026-18110 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 786 88.51%
Telecommunications 42 4.73%
Education 31 3.49%
Business Services 21 2.36%
Government/Politics 3 0.34%
Finance 3 0.34%
Transportation 2 0.23%

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