Medium

Unauthenticated File Usage Disclosure in Concrete CMS

IdentifiersCVE-2026-6826CWE-862

CVE-2026-6826 is an information disclosure vulnerability in Concrete CMS affecting version 9.5.0 and earlier 9.x releases before 9.5.1. The issue is caused by a missing authorization check in the file usage controller exposed through the /ccm/system/dialogs/file/usage/{fID} functionality. An unauthenticated requester can supply arbitrary file identifiers and retrieve file usage metadata showing which pages reference a given file. Disclosed data includes page identifiers, page handles, version information, and full page locations or URLs. Because the endpoint does not enforce the expected view permission check, it can reveal references to pages that are otherwise access-restricted.

For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

Start free trial

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows unauthenticated disclosure of internal content relationships and page metadata from a Concrete CMS instance. An attacker can enumerate file identifiers and map files to referencing pages, including restricted pages, exposing page IDs, handles, version details, and full locations. This can leak sensitive site structure information and facilitate reconnaissance against non-public content, but the available information indicates no direct integrity or availability impact.

Mitigation

If you can’t patch tonight, do this now.

If immediate upgrade is not possible, restrict unauthenticated access to the affected dialog endpoint through application-layer or web-server access controls, and limit exposure of the Concrete CMS administrative and system paths to trusted users or networks where operationally feasible. Monitoring for repeated requests against file usage dialog functionality can help detect enumeration attempts until a fixed release is deployed.

Remediation

Patch, then assume compromise.

Upgrade Concrete CMS to version 9.5.1 or later, where the missing permission check in the file usage functionality is addressed. Validate that the affected endpoint enforces authorization before returning file usage information.

PUBLIC EXPLOITS

Exploits

No valid public exploits. Mallory filtered out 1 candidate as fakes, detection scripts, or README-only repos.

VALID 0 / 1 TOTALView more in app

All candidate exploits were filtered out by Mallory's validation.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

Concrete CMSConcrete Cmsapplication

Concrete5Concrete5application

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

3 SOURCESView more in app

nuclei templates pull requestsNews

Aug 8, 2026

Add CVE-2026-6826 template by str4k3r · Pull Request #16805 · projectdiscovery/nuclei-templates · GitHub

Unknown

metasploit pull requestsNews

Jul 21, 2026

Add Concrete CMS unauthenticated file usage disclosure module by zoomdbz · Pull Request #21695 · rapid7/metasploit-framework · GitHub

An unauthenticated information disclosure vulnerability in Concrete CMS 9.x before 9.5.1 caused by a missing view permission check on the /ccm/system/dialogs/file/usage/<fID> endpoint, allowing enumeration of file IDs and disclosure of associated page metadata.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

Start free trial

Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity1