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Concrete CmsApplication · Concretecms

CVE-2026-8240

MEDIUM · 5.3 CVSS v3.1 Published 2026-05-21
Fix available
A fix is available. Upgrade to 9.5.1 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 9.5.0 and below is vulnerable to unauthenticated page metadata disclosure across every page with a configured summary template, revealing the existence of private, draft, and restricted pages while leaking title, path, description, and author information. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker 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 · high confidence

Unauthenticated attackers can access page metadata (title, path, description, author) through summary templates in Concrete CMS 9.5.0 and below, revealing the existence and details of private, draft, and restricted pages without any authentication or user interaction.

MitigationApply the vendor patch or upgrade to a fixed version of Concrete CMS to remediate the access control bypass in summary templates.

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:< 9.5.1

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
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

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

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
    Check the version number in your Concrete CMS installation - typically found in the dashboard under 'Dashboard > System & Settings > Basics > Site Information' or in a version file in the installation directory.
    Affected if The installed version is 9.5.0 or below (versions prior to 9.5.1)
  2. Confirm summary template feature is in use
    Examine your Concrete CMS installation for active use of the summary template feature - this is typically used in page templates, blocks, or theme templates that render page metadata summaries.
    Affected if Summary templates are enabled and used to render page metadata on your site
  3. Test for unauthenticated metadata disclosure on private pages
    Without authentication, attempt to access summary template output for pages that are marked as private, in draft status, or have restricted access - observe whether metadata such as title, path, description, or author is returned in the response.
    Affected if Private, draft, or restricted pages expose their metadata (title, path, description, author) to unauthenticated users through summary templates
  4. Verify authorization on summary template routing
    Inspect the routing and controller logic for summary template endpoints - check if the code includes authorization checks before returning page metadata.
    Affected if Summary template endpoints do not enforce authorization checks and return metadata for non-public pages without authentication

You are affected if your Concrete CMS installation is version 9.5.0 or below AND the summary template feature is accessible to unauthenticated users, allowing disclosure of metadata from private, draft, or restricted pages.

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

Apply the vendor patch or upgrade to a fixed version of Concrete CMS to remediate the access control bypass in summary templates.

Recommended fix High confidence

9.5.1

  1. Back up the current Concrete CMS installation and database before proceeding
  2. Download Concrete CMS version 9.5.1 or later from the official Concrete CMS website
  3. Follow the official upgrade instructions at documentation.concretecms.org to apply the update
  4. Verify the fix by confirming that unauthenticated users can no longer access metadata (title, path, description, author) on private, draft, or restricted pages with summary templates

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
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

Scan for this in your stack

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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-2026-8240 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