PatchTheCVECVE-2026-18421: Concrete CMS 9 through 9.5.2 does not perform an authorization check in three actions of the Boards data sourc
CVE-2026-18421 is a low-severity flaw (CVSS 2.1) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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
Why this priority
- No elevated risk signals yet
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 2.1 (Low) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | High |
| User interaction | None |
| EPSS exploit chance | 0.4% (top 62%) |
| CISA exploited list | No |
| Weakness | CWE-862 |
| Published | 2026-09-15 |
| Last modified | 2026-09-16 |
Last updated 2026-09-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-18421?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-18421 being exploited?
CVE-2026-18421 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-18421 affect?
CVE-2026-18421 affects affected software. Severity is low (CVSS 2.1). 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
How urgent is CVE-2026-18421?
Priority 17/100. No elevated risk signals yet.