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CVE-2026-81908— Missing Authorization in Concrete CMS 9.2.0 to 9.5.2 REST API Groups List Endpoint Allows Authenticated Users to Enumerate All Groups

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 9.2.0 至 9.5.2 版本的 REST API “组（Groups）列表”接口存在授权缺失漏洞。位于 中的 方法注册了一个权限检查器回调，该回调无条件返回 ，导致在返回组集合时，并未对每个对象（树节点）执行具体的授权检查。 这意味着，只要某个已认证用户的 API token 包含 作用域，该用户即可调用 ，从而获取站点上的所有组信息，无视这些组上的查看权限限制。此漏洞会泄露组织的组结构、角色以及访问层级信息。 Concrete CMS 安全团队为该漏洞分配的 CVSS v4.0 评分

CVSS 6.0 · Medium
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I. Basic Information for CVE-2026-81908

Vulnerability Information
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Vulnerability Title
Missing Authorization in Concrete CMS 9.2.0 to 9.5.2 REST API Groups List Endpoint Allows Authenticated Users to Enumerate All Groups
Source: CVE Program / CVE List V5
Vulnerability Description
Concrete CMS 9.2.0 to 9.5.2 contain a missing authorization vulnerability in the REST API Groups list endpoint. The listGroups() method in concrete/src/Api/Controller/Groups.php registers a permissions checker callback that unconditionally returns true, so no per-object (tree node) authorization is enforced when the group collection is returned. An authenticated user whose API token carries the groups:read scope can call GET /ccm/api/1.0/groups and receive every group on the site regardless of the view permissions on those groups, disclosing the organization's group structure, roles, and access hierarchy. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/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:L/UI:N/VC:H/VI:N/VA:N/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 9.2.0 ~ 9.5.2 -

II. Public POCs for CVE-2026-81908

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III. Intelligence Information for CVE-2026-81908

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Vendor Pages for CVE-2026-81908 (1)

Same Patch Batch · Concrete CMS · 2026-09-11 · 5 CVEs total

CVE-2026-18122 6.0 MEDIUM Concrete CMS 9.2.0 to 9.5.2 Express REST API list endpoint exposes restricted Express entr
CVE-2026-68528 6.0 MEDIUM Concrete CMS 9.5.2 and below is vulnerable to Stored XSS in RSS Displayer Block via Unesca
CVE-2026-81909 5.9 MEDIUM Concrete CMS 9 through 9.5.2 is vulnerable to Missing Authorization in the orphaned-block
CVE-2026-81910 5.9 MEDIUM Concrete CMS 9 through 9.5.2 is vulnerable to Server-Side Template Injection (SSTI) in The

IV. Related Vulnerabilities

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

V. Comments for CVE-2026-81908

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