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CVE-2026-18421— Concrete CMS 9.0.0-9.5.2 Boards data source dashboard is missing an authorization check, allowing a low-privileged board editor to modify or delete configured data sources on boards they do not control

Quick assessment

Affected
Concrete CMS Concrete CMS
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Concrete CMS 9 至 9.5.2 版本中，Boards 数据源仪表板控制器中的三个操作（update、update_data_source 和 delete_data_source）未执行授权检查。这些操作直接根据攻击者提供的标识符解析 ConfiguredDataSource，而未验证请求者对所属 Boards 的编辑权限。因此，仅被授予单个 Board 的 edit_board_settings 权限的用户，便可以修改或永久删除站点上其他任意 Board 的配置数据源，从而导致受影响的 Board

CVSS 2.1 · Low

Possible ATT&CK Techniques 1 AI

T1078 · Valid Accounts

Affected Version Matrix 1

VendorProduct Version RangeStatus
Concrete CMS Concrete CMS 9.0.0≤ 9.5.2 affected
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I. Basic Information for CVE-2026-18421

Vulnerability Information
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Vulnerability Title
Concrete CMS 9.0.0-9.5.2 Boards data source dashboard is missing an authorization check, allowing a low-privileged board editor to modify or delete configured data sources on boards they do not control
Source: CVE Program / CVE List V5
Vulnerability Description
Concrete CMS 9 through 9.5.2 does not perform an authorization check in three actions of the Boards data source dashboard controller (update, update_data_source, and delete_data_source), which resolve a ConfiguredDataSource directly from an attacker-supplied identifier without confirming the requester's edit permission on the owning board. A user granted edit_board_settings on a single board was therefore able to modify or permanently delete the configured data sources of any other board on the site, halting the affected board's content feed and resetting its custom weighting. The CSRF token that guards these actions was validated but bound to the action name rather than to the target object, so a token legitimately obtained for one board could be replayed against another board's ConfiguredDataSource identifier and did not constrain access. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制缺失
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Concrete CMS Concrete CMS 9.0.0 ~ 9.5.2 -

II. Public POCs for CVE-2026-18421

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III. Intelligence Information for CVE-2026-18421

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Vendor Pages for CVE-2026-18421 (1)

Same Patch Batch · Concrete CMS · 2026-09-15 · 31 CVEs total

CVE-2026-18110 8.7 HIGH Concrete CMS 9.0.0 through 9.5.2 is vulnerable to missing authorization in the user select
CVE-2026-81894 8.5 HIGH Concrete CMS 9.5.2 and below is vulnerable to Stored DOM-based Cross-site Scripting (XSS)
CVE-2026-18111 8.5 HIGH Concrete CMS below 9.5.4 allows privilege escalation because adding users and assigning gr
CVE-2026-81895 8.5 HIGH Concrete CMS 9.5.2 and below is vulnerable to Stored SQL Injection in Concrete CMS Documen
CVE-2026-81896 8.4 HIGH Concrete CMS below version 9.5.3 is vulnerable to Stored XSS in Concrete CMS Form Submissi
CVE-2026-81897 7.7 HIGH Concrete CMS below version 9.5.3 is vulnerable to Stored XSS via Express form Text control
CVE-2026-81898 7.5 HIGH Concrete CMS below version 9.5.3 is vulnerable to Stored XSS via country-less Address att
CVE-2026-18113 7.5 HIGH Concrete CMS 9.0 to 9.5.2 is vulnerable to Stored XSS in the Top Navigation Bar Block via
CVE-2026-18115 7.4 HIGH In Concrete CMS 9.2.0 to 9.5.2, Missing Authorization in REST API Users update() and chang
CVE-2026-81899 7.3 HIGH Concrete CMS 9.0 to 9.5.2 is vulnerable to Stored XSS via group folder name on the Members
CVE-2026-68533 2.3 LOW Missing Authorization in Concrete CMS versions below 9.5.3 Conversation File Upload Allows
CVE-2026-81921 2.3 LOW In Concrete CMS 8.5.3 to 9,5,2, OAuth 2.0 Refresh-Token Grant Bypasses Account Status
CVE-2026-81920 2.3 LOW Concrete CMS below 9.5.3 is vulnerable to Cross-Site Request Forgery (CSRF) in Dashboard S
CVE-2026-68532 2.3 LOW Concrete CMS 9.0.0 to 9.5.2 is vunerable to CSRF in Concrete CMS Group Type Deletion Dashb
CVE-2026-68534 2.3 LOW Concrete CMS below 9.5.2 is vulnerable to Stored XSS via unescaped Express entry labels in
CVE-2026-81919 2.3 LOW Concrete CMS below 9.5.3 is vulnerable to Cross-Site Request Forgery (CSRF) in Block Arran
CVE-2026-81922 2.1 LOW "In Concrete CMS below 9.5.3, there is Missing authorization in the sitemap page reorder a
CVE-2026-81925 2.1 LOW Concrete CMS below 9.5.3 is vulnerable to Reflected Cross-Site Scripting (XSS) via Convers
CVE-2026-18424 2.1 LOW Concrete CMS 9.0.0 to 9.5.2 is vulnerable to SSRF protection bypass in remote file import
CVE-2026-18425 2.1 LOW IDOR in Concrete CMS 9.0.0 through 9.5.2 dashboard sitemap reorder (SitemapUpdate::updateD

Showing top 20 of 31 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Concrete CMS
Same vendor: Concrete CMS
Same weakness: CWE-862

V. Comments for CVE-2026-18421

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