Vulnerability in Concrete CMS (CVE-2026-81908)
Summary
Vulnerability in Concrete CMS (CVE-2026-81908). Risk of unauthorized operations or information disclosure. Exploitable via GET /ccm/api/1.0/groups.
Original description
The description as published by the source.
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: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-81908 has been found in Concrete CMS.
Attackers can target a specific entry point like GET /ccm/api/1.0/groups over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Concrete CMS CVE-2026-81908" on the vendor's site.
CVE-2026-81908 (Concrete CMS) — CWE-862
Attack surface: GET /ccm/api/1.0/groups
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-862) exists in Concrete CMS. Attackers reach the vulnerable code path via GET /ccm/api/1.0/groups.
Check the vendor advisory for the affected versions of Concrete CMS. Attack surface: GET /ccm/api/1.0/groups.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual GET /ccm/api/1.0/groups requests with malformed payloads or SQL meta-characters. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Concrete CMS を使っているサービスとバージョンを洗い出す。
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2Hunt for indicators of compromise detect
grep 'GET /ccm/api/1.0/groups' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
GET /ccm/api/1.0/groupsへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Post-deployment verification verify
Replay attack against GET /ccm/api/1.0/groups on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。
References
- web documentation.concretecms.org
- web nvd.nist.gov
- web github.com