CVE-2026-8409
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 · uneditedConcrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/dialog/logs/delete. The 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 · high confidenceThis is a Cross Site Request Forgery (CSRF) vulnerability in Concrete CMS version 9.x before 9.5.0. The vulnerability exists at the concrete/controllers/dialog/logs/delete endpoint, allowing attackers to trick authenticated administrators into unknowingly deleting log files via malicious requests. The discrepancy between CVSS v3.1 (8.8 HIGH) and v4.0 (2.3 low) reflects the different scoring methodologies, with v4.0 more accurately capturing the limited scope of impact (log deletion only, no data confidentiality compromise).
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>= 9.0.0, < 9.5.1CVSS 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 checksWork through these to decide whether this CVE applies to you.
-
Determine installed Concrete CMS versionAccess the admin dashboard and navigate to Dashboard > System Information > Overview to view the CMS version. Alternatively, check the file concrete/CHANGELOG.md or the version constant in concrete/src/Application/Service/Application.phpAffected if The installed version is 9.0.0 through 9.5.0 (any version >= 9.0.0 and < 9.5.1)
-
Verify logs deletion endpoint existsLocate the file concrete/controllers/dialog/logs/delete.php or concrete/controllers/dialog/logs/Delete.php in the installation directoryAffected if The delete.php controller file exists in the logs dialog folder, indicating the vulnerable endpoint is present
-
Confirm admin authentication statusCheck if there are authenticated administrator sessions in the Concrete CMS environment by reviewing the database table for active sessions or reviewing authentication configuration in concrete/config/app.phpAffected if Administrators have active sessions and can access the logs deletion functionality
-
Inspect for anti-CSRF protection on state-changing operationsExamine the logs delete controller and associated view templates for presence of CSRF tokens (typically using $token->generate or similar token validation). Check if the delete action validates a CSRF token before executing the deletionAffected if No anti-CSRF token validation is implemented on the logs delete action, leaving it vulnerable to CSRF attacks
The environment is affected if the installed Concrete CMS version is 9.0.0 or higher but lower than 9.5.1, and the logs deletion endpoint exists without proper CSRF token protection.
Generated from the published advisory. Verify against your own configuration.
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 · scoped9.5.1
Upgrade to Concrete CMS 9.5.0 or later which contains the fix. Alternatively, implement anti-CSRF tokens on the affected delete action and ensure proper referer/origin header validation.
Concrete CMS 9.5.1 or later
- 1. Back up your Concrete CMS database and files before upgrading.
- 2. Download Concrete CMS version 9.5.1 or later from the official Concrete CMS website or repository.
- 3. Replace the core Concrete CMS files with the new version, preserving your configuration and application files.
- 4. Run any database migrations if required by the upgrade process.
- 5. Verify the application functions correctly after the upgrade.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-8409 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-8409 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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