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Concrete CmsApplication · Concretecms

CVE-2021-22951

HIGH · 7.5 CVSS v3.1 Published 2021-11-19
Fix available
A fix is available. Upgrade to 8.5.7 or later.
See remediation →
84/100
Remediation priority · High
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
Unauthorized individuals could view password protected files using view_inline in Concrete CMS (previously concrete 5) prior to version 8.5.7. Concrete CMS now checks to see if a file has a password in view_inline and, if it does, the file is not rendered.For version 8.5.6, the following mitigations were put in place a. restricting file types for view_inline to images only b. putting a warning in the file manager to advise users.Credit for discovery: "Solar Security Research Team"Concrete CMS security team CVSS scoring is 5.3: AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NThis fix is also in Concrete version 9.0.0

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 before 8.5.7 had an information disclosure vulnerability where the view_inline function allowed unauthorized access to password-protected files. The view_inline endpoint did not check whether a file had password protection enabled before rendering it, allowing anyone with the direct file URL to bypass the password requirement and view the file contents.

MitigationUpgrade Concrete CMS to version 8.5.7 or 9.0.0 which implements password verification in the view_inline function. As an interim measure for version 8.5.6, restrict view_inline to image file types only and warn users about the vulnerability in the file manager.

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:< 8.5.7

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
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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 Concrete CMS installed version
    Check the dashboard under Dashboard > System & Settings > Basics > Site Name or inspect the application/config/version.php file if it exists. Compare the version number to the vulnerable range (before 8.5.7).
    Affected if Installed version is 8.5.6 or lower, or any version below 8.5.7 (including 9.x versions below 9.0.0).
  2. Determine if view_inline endpoint is accessible
    Check if the /index.php/download_file/view_inline/ or /ccm/api/v1/files/view_inline endpoint responds without authentication. This is the vulnerable endpoint that should not render password-protected files.
    Affected if The endpoint returns file contents without prompting for a password or requiring authentication.
  3. Check for password-protected files
    In the File Manager (Dashboard > Files > Files), review files that have password protection enabled (indicated by a lock icon or password protection setting). Note the direct file URLs for these protected files.
    Affected if Password-protected files exist in the system and can be accessed via direct URL without password prompt.
  4. Verify password protection bypass
    Attempt to access a known password-protected file using its direct URL (e.g., /index.php/download_file/view_inline/FILE_ID). Observe whether the file content renders without requiring password entry.
    Affected if The file renders completely without any password prompt, confirming the bypass vulnerability exists.

You are affected if your Concrete CMS version is before 8.5.7 (or before 9.0.0 for the 9.x branch) and password-protected files can be accessed via the view_inline endpoint without entering a password.

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 8.5.7 or later
Fixed in 8.5.7
Interim mitigation

Upgrade Concrete CMS to version 8.5.7 or 9.0.0 which implements password verification in the view_inline function. As an interim measure for version 8.5.6, restrict view_inline to image file types only and warn users about the vulnerability in the file manager.

Recommended fix High confidence

Concrete CMS 8.5.7 or 9.0.0

  1. Backup the current Concrete CMS database and files before proceeding with any upgrade
  2. Download Concrete CMS version 8.5.7 or 9.0.0 from the official Concrete CMS repository or download page
  3. Review the official upgrade guide for the target version at documentation.concretecms.org
  4. Upload the new files to the server, replacing the existing installation
  5. Run the database upgrade process through the Concrete CMS dashboard or command line
  6. Verify that password-protected files are no longer accessible via view_inline without authentication
  7. Test that image files render correctly through view_inline after the upgrade

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

Fix this in Concrete Cms Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

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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-2021-22951 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