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CVE-2026-18110

7.5, high

Concrete CMS Missing Authorization Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
7.5, high high CVSS v3.1
EPSS, next 30 days
0.3% higher than 17.6% of scored CVEs
Exploitation
No public evidence
Published
15 Sept 2026a month ago

Description

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.

Details

Vendor
Concrete CMS
Product
Concrete CMS
Weakness
CWE-862 (opens in a new tab)
Status
Analyzed
Updated
22 Sept 2026
Assigner
ff5b8ace-8b95-4078-9743-eac1ca5451de

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References 1

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Concrete CMS CVEs

Every Concrete CMS CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-85385 Concrete CMS Cross-Site Scripting Vulnerability EPSS 0.5% 9.6, critical
  • CVE-2026-85387 Concrete CMS Insufficient Session Expiration Vulnerability EPSS 0.3% 7.1, high
  • CVE-2026-81895 Concrete CMS SQL Injection Vulnerability EPSS 0.5% 7.2, high
  • CVE-2026-18423 Concrete CMS Authorization Bypass Through User-Controlled Key Vulnerability EPSS 0.2% 7.1, high
  • CVE-2026-18424 Concrete CMS Server-Side Request Forgery Vulnerability EPSS 0.2% 7.1, high
  • CVE-2026-18119 Concrete CMS Cross-Site Scripting Vulnerability EPSS 0.3% 9, critical
  • CVE-2026-81901 Concrete CMS Missing Authorization Vulnerability EPSS 0.4% 8.7, high
  • CVE-2026-81902 Concrete CMS Cross-Site Request Forgery Vulnerability EPSS 0.2% 8.1, high

Beyond this page

Is CVE-2026-18110 in your network?

This page tells you how dangerous CVE-2026-18110 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

  • EXYS7600 OCELOT

    Find it before attackers do

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 18 Oct 2026, not the live upstream state.