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Concrete CmsApplication · Concretecms

CVE-2026-8245

MEDIUM · 5.4 CVSS v3.1 Published 2026-05-21
Fix available
A fix is available. Upgrade to 9.5.1 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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 Reflected XSS in Legacy Pagination via HTML attribute injection. Concrete\Core\Legacy\Pagination builds pagination links by raw-interpolating its $URL field into href="" (<a href="{$linkURL}" …>). Any authenticated admin or report viewer with access to `/dashboard/reports/forms/legacy` who clicks the crafted URL fires the payload in their session. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/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 · high confidence

Concrete CMS versions 9.5.0 and below contain a reflected XSS vulnerability in the Legacy Pagination component (Concrete\Core\Legacy\Pagination). The component builds pagination links by raw-interpolating the $URL field directly into an HTML href attribute without sanitization, allowing injection of malicious JavaScript via a crafted URL parameter.

MitigationThe $URL field must be properly encoded before interpolation into the href attribute. The fix requires applying HTML attribute encoding (escaping special characters like quotes and angle brackets) to the URL value in the Pagination class template.

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
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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. Check Concrete CMS installed version
    Locate the version file or dashboard footer version display. Common locations: /concrete/config/app.php or through the admin dashboard. Compare your version number against 9.5.1.
    Affected if Your installed version is below 9.5.1 (e.g., 9.5.0, 9.4.x, or earlier)
  2. Verify Legacy Pagination component exists
    Check for the file Concrete\Core\Legacy\Pagination in your installation. This class handles pagination across the CMS.
    Affected if The Concrete\Core\Legacy\Pagination class exists in your codebase and is being used
  3. Inspect Pagination for raw URL interpolation
    Examine the Concrete\Core\Legacy\Pagination file for the $URL variable being inserted into HTML href attributes without sanitization (no htmlspecialchars, no escape function).
    Affected if The $URL field is directly interpolated into href attributes without output encoding functions
  4. Check for access to vulnerable endpoint
    Verify if the path /dashboard/reports/forms/legacy is accessible. This requires authentication as admin or report viewer.
    Affected if You have authenticated access to the /dashboard/reports/forms/legacy route in your Concrete CMS instance

You are affected if your Concrete CMS version is below 9.5.1 and the Legacy Pagination component uses the $URL field without sanitization in href attributes accessible through /dashboard/reports/forms/legacy.

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

The $URL field must be properly encoded before interpolation into the href attribute. The fix requires applying HTML attribute encoding (escaping special characters like quotes and angle brackets) to the URL value in the Pagination class template.

Recommended fix High confidence

Concrete CMS 9.5.1

  1. Create a complete backup of the database and files (including composer.json, site configuration)
  2. Download Concrete CMS 9.5.1 from the official source (concretecms.com) or update via composer
  3. Review the 9.5.1 release notes for any required configuration changes
  4. Upload the new files to the server, overwriting the existing installation
  5. Run any database migrations if required (typically handled by the updater)
  6. Clear all caches via dashboard or CLI: php concrete/bin/concrete concrete:clear-cache
  7. Verify the installation by logging in and checking /dashboard/reports/forms/legacy
  8. Test that pagination works correctly without XSS vulnerability
Caveat Minor patch release; minimal risk - review 9.5.1 release notes for any small configuration changes

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
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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-2026-8245 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