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TI-2026-15137 Aliases CVE-2026-18421GHSA-266p-gm36-gqvf

Missing authorization in Concrete CMS

Priority LOW 12CWE-862Published · Updated

Key facts

Attack vector
Network
Privileges required
High
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
None · Low · Low
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-862.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00441 38th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

No affected products listed by the sources yet.

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*——Concrete CMS
  • cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:* Versions — — ·Concrete CMS

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-18421
  2. 2026-10-03 Alias added: GHSA-266p-gm36-gqvf

References

  • TI-2026-23602 ConcreteCMS v9.4.7 contains a Denial of Service (DoS) vulnerability in the File Manager… CVSS 3.1MEDIUM 6.5
  • TI-2023-23992 A Cross Site Scripting (XSS) vulnerability in Concrete CMS from versions 9.2.0 to 9.2.2… CVSS 3.1MEDIUM 5.4
  • TI-2023-26495 Concrete CMS before 8.5.13 and 9.x before 9.2.2 allows unauthorized access because… CVSS 3.1CRITICAL 9.8
  • TI-2026-14907 Missing authorization in Concrete CMS CVSS 4.0HIGH 8.7
  • TI-2022-06200 Cleartext transmission of sensitive information in https://github.com/concrete5/concrete5 CVSS 3.1CRITICAL 9.8
  • TI-2021-17294 An issue was discovered in Concrete CMS through 8.5.5. CVSS 3.1CRITICAL 9.8
See all 220 →

Sources