CVE-2026-30662: Concrete5/concrete5 Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-p68c-rmfh-j48h
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CVSS 6.5
CWE-770
Published
Advisory Summary

CVE-2026-30662 is a MODERATE (CVSS 6.5) denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Concrete5/concrete5 libraries in the Packagist ecosystem. The issue involves concretecms is vulnerable to denial of service during bulk downloads. Remediation is available in the latest vendor maintenance releases.

CVE-2026-30662 at a Glance

CVE Identifier CVE-2026-30662
GHSA Identifier GHSA-p68c-rmfh-j48h
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product Concrete5/concrete5
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-30662

To remediate this vulnerability, upgrade all affected Concrete5/concrete5 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

concrete5/concrete5 fixed: Latest secure release 
Upgrade concrete5/concrete5 to Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for concrete5/concrete5

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-30662, inspect your project dependencies for Concrete5/concrete5:

inspect dependencies for concrete5/concrete5

Analyze the terminal output to locate any version of Concrete5/concrete5 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In Concrete5/concrete5, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-30662 Affected Concrete5/concrete5 Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
concrete5/concrete5
 Packagist
≤ 9.4.7

References

NVD — CVE-2026-30662 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-30662
Concrete5/concrete5 Source Repository REPOSITORY
https://github.com/concretecms/concretecms
wang1rrr.github.io/2026/02/11/cve-repo... WEB
https://wang1rrr.github.io/2026/02/11/CVE-Report-ConcreteCMS-DoS

Frequently Asked Questions

What is CVE-2026-30662?
CVE-2026-30662 is a security vulnerability in Concrete5/concrete5 involving ConcreteCMS is vulnerable to Denial of Service During Bulk Downloads under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Concrete5/concrete5 versions are affected?
Affected versions include releases prior to current release patches across affected packages: concrete5/concrete5.
What version fixes CVE-2026-30662?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is concrete5/concrete5 affected?
Yes, concrete5/concrete5 is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2026-30662?
CVE-2026-30662 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-30662?
CVE-2026-30662 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check Packagist dependencies for CVE-2026-30662?
Run the dependency tree command: 'inspect dependencies for concrete5/concrete5'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-p68c-rmfh-j48h",
  "modified" : "2026-03-26T18:38:46Z",
  "published" : "2026-03-24T15:30:29Z",
  "aliases" : [ "CVE-2026-30662" ],
  "summary" : "ConcreteCMS is vulnerable to Denial of Service During Bulk Downloads",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "concrete5/concrete5"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "9.4.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-30662"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/concretecms/concretecms"
  }, {
    "type" : "WEB",
    "url" : "https://wang1rrr.github.io/2026/02/11/CVE-Report-ConcreteCMS-DoS"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-26T18:38:46Z",
    "nvd_published_at" : "2026-03-24T15:16:34Z"
  }
}