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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

Medium6.0EPSS 0.39%
Published
Updated
Reserved
Assigned by
ConcreteCMS

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.

Timeline

  1. ID reserved

    By ConcreteCMS

  2. · 15 days later

    Published

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2026-81908, by who scored it
Scored byCVSSScoreVector
ConcreteCMSCNA (assigner)4.0Medium6.0CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
NVDNVD · Deferred4.0Medium6.0CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS (exploitation in 30 days)
0.39% · top 66% of all CVEs (8 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.0.

Weakness

Affected products

References (1)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .