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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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
Which versions are affected by CVE-2026-30662?
2 open source packages ship an affected version, including concrete5/concrete5. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
concrete5/concrete5 Packagist | All versions to 9.4.7 | None |
concrete5/concrete5 Packagist | All versions to 9.4.7 | None |
Products include 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.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
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 Concrete CMS allows unauthorized access because directories can be created with insecure permissions
- CVE-2022-21829 Code injection in concrete CMS
- CVE-2021-22958 Server-Side Request Forgery vulnerability in concrete5
- CVE-2021-40098 Path traversal in n/a
- CVE-2026-8134 Concrete CMS Vulnerable to Relative Path Traversal
Sources
Also known as GHSA-p68c-rmfh-j48h.