# CVE-2026-30662: ConcreteCMS is vulnerable to Denial of Service During Bulk Downloads

> An authenticated attacker can cause a denial of service in ConcreteCMS by triggering an out-of-memory condition during bulk file downloads.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Mar 2026
- **Updated:** 24 Mar 2026
- **Also known as:** GHSA-p68c-rmfh-j48h

## What is CVE-2026-30662?

CVE-2026-30662 is a medium-severity denial of service vulnerability in Concretecms Concrete Cms, published on 24 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

ConcreteCMS v9.4.7 contains a Denial of Service (DoS) vulnerability in the File Manager component. The 'download' method in 'concrete/controllers/backend/file.php' improperly manages memory when creating zip archives. It uses 'ZipArchive::addFromString' combined with 'file_get_contents', which loads the entire content of every selected file into PHP memory. An authenticated attacker can exploit this by requesting a bulk download of large files, triggering an Out-Of-Memory (OOM) condition that causes the PHP-FPM process to terminate (SIGSEGV) and the web server to return a 500 error.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-30662?

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 to 9.4.7 | None |
| `concrete5/concrete5` | Packagist | All versions to 9.4.7 | None |

Products: Concretecms Concrete Cms.

## How do I fix CVE-2026-30662?

No fix has been published for CVE-2026-30662 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-30662 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-30662 exists.

## 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-2026-30662 and fix it if it is affected.

What it is: CVE-2026-30662 is a medium-severity denial of service vulnerability in Concretecms Concrete Cms, published on 24 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-30662 exists.

Affected packages and fixed versions:
- concrete5/concrete5 (Packagist): affected all versions up to 9.4.7; no fix listed
- concrete5/concrete5 (Packagist): affected all versions up to 9.4.7; no fix listed

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-2026-30662/ (Markdown: https://insights.sbomify.com/CVE-2026-30662/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-30662
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-30662
- OSV: https://osv.dev/vulnerability/CVE-2026-30662

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-30662/
Summaries are generated and may contain mistakes; the official description above is the record.