# CVE-2026-84432: Concrete CMS 9 through 9.5.2 is vulnerable to CSRFin the Boards custom slot dialog controller

> Attackers can force users with board-edit permissions to write malicious slot data to boards via cross-site request forgery in Concrete CMS.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 10 Sep 2026
- **Updated:** 10 Sep 2026
- **Also known as:** GHSA-72w5-w82m-7hm9

## What is CVE-2026-84432?

CVE-2026-84432 is a medium-severity vulnerability in Concrete CMS, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Concrete CMS 9 through  9.5.2 did not validate an anti-CSRF token in the Boards custom slot dialog controller (concrete/controllers/dialog/board/custom_slot.php) saveTemplate() action. The action created a board_slot_proxy Block and dispatched an AddCustomSlotToBoardCommand against a board instance while gating only on the per-resource canEditBoardContents() permission, so a crafted cross-site request could cause a user holding board-edit permission with an active session to write attacker-chosen slot and template data to a board under their own authority. The state-changing database write completed before any downstream rendering, so the forged request succeeded even when the HTTP response returned a non-200 status. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Weakness: CWE-352 (Cross-Site Request Forgery)

## Which versions are affected by CVE-2026-84432?


## How do I fix CVE-2026-84432?

No fix has been published for CVE-2026-84432 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-84432 being exploited?

There is no known exploitation of CVE-2026-84432 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84432 and fix it if it is affected.

What it is: CVE-2026-84432 is a medium-severity vulnerability in Concrete CMS, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-84432 in the wild and no public exploit code.

Affected product: Concrete CMS. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-84432/ (Markdown: https://insights.sbomify.com/CVE-2026-84432/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84432
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84432
- OSV: https://osv.dev/vulnerability/CVE-2026-84432

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-84432/
Summaries are generated and may contain mistakes; the official description above is the record.