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Concrete CmsApplication · Concretecms

CVE-2026-8412

HIGH · 8.8 CVSS v3.1 Published 2026-05-21
Fix available
A fix is available. Upgrade to 9.5.1 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/dialog/page/bulk/cache. 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:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori (Tenzai) for reporting.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Cross-Site Request Forgery (CSRF) vulnerability in Concrete CMS 9 before 9.5.0 at the bulk cache controller endpoint (concrete/controllers/dialog/page/bulk/cache). The affected endpoint lacks proper anti-CSRF token validation, allowing attackers to trick authenticated administrators into performing unintended cache management actions.

MitigationImplement anti-CSRF token validation on the affected bulk cache endpoint. Upgrade to Concrete CMS 9.5.0 or later which contains the security fix.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Concrete CmsApplication
Affected:>= 9.0.0, < 9.5.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Concrete CMS version
    Access the dashboard and navigate to Dashboard > System & Settings > Basics > Site Name, or check the version.php file in the application/config directory if you have file system access. The version is typically displayed on the dashboard footer or in the version file.
    Affected if Installed version is 9.0.0 through 9.5.0 (versions >= 9.0.0 and < 9.5.1 are affected)
  2. Locate the vulnerable bulk cache endpoint
    Verify the existence of the file concrete/controllers/dialog/page/bulk/cache.php in the web root. This is the endpoint handling bulk cache operations that lacks CSRF protection.
    Affected if The file concrete/controllers/dialog/page/bulk/cache.php exists in the installation and the CMS version falls within the affected range
  3. Check access to bulk cache operations
    Log in as an authenticated user with page editing permissions. Navigate to the page tree in the dashboard, select multiple pages, and look for bulk operations that include cache manipulation options (clear cache, refresh cache, etc.).
    Affected if The bulk cache operations feature is accessible to authenticated users in versions within the affected range
  4. Verify CSRF protection status on the endpoint
    Examine the cache.php controller file for presence of anti-CSRF token validation. Look for calls to $this->validateCSRFToken() or similar validation methods within the controller handling POST requests.
    Affected if The bulk cache endpoint lacks CSRF token validation and the CMS version is within the affected range

A user is affected if they are running Concrete CMS version 9.0.0 through 9.5.0 and have the bulk cache operations feature accessible to authenticated users without CSRF protection on that endpoint.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 9.5.1 or later
Fixed in 9.5.1
Interim mitigation

Implement anti-CSRF token validation on the affected bulk cache endpoint. Upgrade to Concrete CMS 9.5.0 or later which contains the security fix.

Recommended fix High confidence

Concrete CMS 9.5.1 or latest stable 9.x release

  1. 1. Backup your entire Concrete CMS installation including database and files
  2. 2. Review the Concrete CMS 9.5.1 release notes for any migration requirements
  3. 3. Place your site in maintenance mode via the dashboard or by creating a /application/config/site.php maintenance flag
  4. 4. Download Concrete CMS version 9.5.1 or the latest stable 9.x release from the official source
  5. 5. Replace core files, preserving your /application directory and any custom code
  6. 6. Run any database migrations if required by navigating to /index.php/ccm/system/upgrade or using the CLI
  7. 7. Clear all caches via the dashboard or CLI (concrete/bin concrete5 cache:clear)
  8. 8. Test critical functionality including the bulk cache operation at /ccm/system/dialogs/page/bulk/cache
Caveat Review 9.5.x release notes for any breaking changes between your current version and 9.5.1

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Concrete Cms Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-8412 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data