CVE-2026-8414 Concrete CMS CVE debrief

Who should care

Concrete CMS administrators, site owners, and anyone maintaining Concrete CMS 9 installations before 9.5.0, especially environments where authenticated users can reach the affected dialog controller.

Technical summary

The issue is classified as CSRF (CWE-352) with an additional CWE-1275 mapping in the supplied metadata. The NVD record gives CVSS v4.0 2.3 (AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N), indicating network-reachable impact that requires user interaction and is limited in integrity effect. The affected area is concrete/controllers/dialog/event/duplicate in Concrete CMS 9 before 9.5.0.

Defensive priority

Routine patching, but prioritize updating affected Concrete CMS 9 systems promptly because the flaw can let a victim browser perform unintended authenticated actions.

Recommended defensive actions

• Confirm whether any Concrete CMS 9 instances are running versions earlier than 9.5.0.
• Upgrade affected installations to a version that includes the fix referenced by the Concrete CMS security update.
• Review administrative and authenticated workflows that reach concrete/controllers/dialog/event/duplicate for CSRF protections and token validation.
• Check for suspicious state-changing requests involving authenticated users around the affected area.
• If immediate upgrading is not possible, limit access to administrative interfaces and reduce exposure of sensitive authenticated actions.

Evidence notes

The CVE description supplied with the record states that Concrete CMS 9 before 9.5.0 is vulnerable to CSRF at concrete/controllers/dialog/event/duplicate and assigns CVSS v4.0 2.3. The NVD metadata lists the same CVE on 2026-05-21 and includes a Concrete CMS documentation release-notes reference. The vendor field in the supplied corpus is low-confidence/needs-review, so the product attribution is based on the CVE description and NVD reference rather than the vendor field.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.