# CVE-2026-8347: Concrete CMS 9.5.0 and below is vulnerable to IDOR + wrong-authorization-level in Express association Reorder dialog

> Attackers with view-only permissions can tamper with Express entity ordering due to improper authorization checks in Concrete CMS.

- **Severity:** Low 2.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 May 2026
- **Updated:** 22 May 2026
- **Also known as:** GHSA-jqvq-gv67-3567

## What is CVE-2026-8347?

CVE-2026-8347 is a low-severity missing authorization vulnerability in Concretecms Concrete Cms, published on 22 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Concrete CMS 9.5.0 and below is vulnerable to IDOR + wrong-authorization-level in the Express association Reorder dialog.  This can cause Cross-entity state tampering with view-only permission on one entry. To be affected, a website has to be using express and relying on express entity ordering. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-8347?

2 open source packages ship an affected version, including concrete5/concrete5. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `concrete5/concrete5` | Packagist | All versions | 9.5.1 |
| `concrete5/concrete5` | Packagist | All versions | 9.5.1 |

Products: Concretecms Concrete Cms.

## How do I fix CVE-2026-8347?

Upgrade concrete5/concrete5 to 9.5.1 or later.

## Is CVE-2026-8347 being exploited?

There is no known exploitation of CVE-2026-8347 in the wild and no public exploit code.

Public exploit code:

- CVE-2026-8347 is an Insecure Direct Object Reference (IDOR) combined with a wrong authorization level vulnerability in Concrete CMS versions 9.5.0 and earlier. The flaw exists in the Express association Reorder dialog, allowing a user with only view permissions on an Express entry to modify the ordering of associations for another entity. (github_poc): https://github.com/aj2108/CVE-2026-8347

## Other vulnerabilities in Concretecms Concrete Cms

- [CVE-2023-48648](https://insights.sbomify.com/CVE-2023-48648/): Concrete CMS allows unauthorized access because directories can be created with insecure permissions (critical 9.8)
- [CVE-2022-21829](https://insights.sbomify.com/CVE-2022-21829/): Code injection in concrete CMS (critical 9.8)
- [CVE-2021-22958](https://insights.sbomify.com/CVE-2021-22958/): Server-Side Request Forgery vulnerability in concrete5 (critical 9.8)
- [CVE-2021-40098](https://insights.sbomify.com/CVE-2021-40098/): Path traversal in n/a (critical 9.8)
- [CVE-2026-8134](https://insights.sbomify.com/CVE-2026-8134/): Concrete CMS Vulnerable to Relative Path Traversal (critical 9.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-8347 and fix it if it is affected.

What it is: CVE-2026-8347 is a low-severity missing authorization vulnerability in Concretecms Concrete Cms, published on 22 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-8347 in the wild and no public exploit code.

Affected packages and fixed versions:
- concrete5/concrete5 (Packagist): affected all versions; fixed in 9.5.1
- concrete5/concrete5 (Packagist): affected all versions; fixed in 9.5.1

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-2026-8347/ (Markdown: https://insights.sbomify.com/CVE-2026-8347/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8347
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8347
- OSV: https://osv.dev/vulnerability/CVE-2026-8347

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-8347/
Summaries are generated and may contain mistakes; the official description above is the record.