---
id: CVE-2026-18424
title: >-
  Concrete CMS 9.0.0 to 9.5.2 is vulnerable to Server-Side Request Forgery
  iremote file import via cross-port reuse of a host's validated DNS pin
summary: >-
  Concrete CMS 9.0.0 to 9.5.2 is vulnerable to Server-Side Request Forgery
  iremote file import via cross-port reuse of a host's validated DNS pin. When
  multiple remote URLs share the same host, only the first `ValidatedRemoteUrl`
  is retain…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N'
cwe:
  - CWE-918
vendor: concretecms
product: concrete_cms
affected:
  - 'concrete_cms >= 9.0.0, < 9.5.3'
patched:
  - concrete_cms 9.5.3
published: '2026-09-15'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T17:50:50.450'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-18424'
references:
  - url: >-
      https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes
    label: ff5b8ace-8b95-4078-9743-eac1ca5451de
tags:
  - nvd
  - cve.org
  - score-dispute
epss: 0.00238
epssPercentile: 0.13228
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-20T00:41:04.561434Z'
scores:
  nvd: 7.1
  cna: 2.1
ingestedAt: '2026-09-15T20:44:02.398Z'
---

## Overview

Concrete CMS 9.0.0 to 9.5.2 is vulnerable to Server-Side Request Forgery iremote file import via cross-port reuse of a host's validated DNS pin. When multiple remote URLs share the same host, only the first `ValidatedRemoteUrl` is retained and reused for every later URL with that host. A low-privileged authenticated user permitted to import files could therefore supply a DNS-rebinding host that resolved to a public address during validation and to a private or loopback address during the unpinned download, causing the server to fetch internal-only resources such as loopback services, internal admin panels, or cloud metadata endpoints and to save the responses into the file manager. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N. Thanks Ahmad Wicaksono (sonix03) for reporting.

## Affected

- `concrete_cms >= 9.0.0, < 9.5.3`

## Remediation

Upgrade past the affected range:

- `concrete_cms 9.5.3`