PatchTheCVECVE-2026-81909: Concrete CMS 9 through 9.5.2 is vulnerable to Missing Authorization in the block alias route (Process::alias()
CVE-2026-81909 is a medium-severity flaw (CVSS 5.9) 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 is vulnerable to Missing Authorization in the block alias route (Process::alias() in concrete/controllers/backend/block/process.php).It does not verify that the referenced block is genuinely orphaned on the target page, nor that the caller holds any permission over the source block. A user granted only an area-scoped add_block_to_area delegation on their own page can therefore pass any block ID on the site: the source
Why this priority
- No elevated risk signals yet
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 5.9 (Medium) |
| 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 | 2026-09-11 |
| Last modified | 2026-09-11 |
Last updated 2026-09-11 · 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-2026-81909?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-81909 being exploited?
CVE-2026-81909 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-2026-81909 affect?
CVE-2026-81909 affects affected software. Severity is medium (CVSS 5.9). Concrete CMS 9 through 9.5.2 is vulnerable to Missing Authorization in the block alias route (Process::alias() in concrete/controllers/backend/block/process.php).It does not verify that the referenced block is genuinely orphaned on the targ
How urgent is CVE-2026-81909?
Priority 30/100. No elevated risk signals yet.