CVE-2026-68535
CVE-2026-68535 — Concrete CMS 9.2.0 to 9.5.2 is vulnerable to Missing authorization in the Concrete CMS Area REST API block-create path letting an editor reference files outside their file-manager permissions
Concrete CMS Area API's block-create endpoint in versions 9.2.0 to 9.5.2 did not invoke the block type controller's validate() method on submitted data, which, for file-referencing blocks such as hero_image and gallery, is where the referenced file is authorized against the user's file-manager visibility. As a result, an authenticated user holding the block-add scope could store, and cause the page to render, a reference to a file that the file-manager authorization policy would otherwise reject, disclosing that file's URL and preview to the editor and to visitors of the affected page. Under public file storage, the URL and thumbnail are exposed directly; under private storage, the disclosure is limited by the permission-checked download URL. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.1 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.
Published Updated Sources: NVD, Concrete CMS (CNA), GitHub, GitHub Security Advisory, SOCRadar CTI
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Unreported
no source claims exploitation
EPSS
0%
ahead of 0% of scored CVEs
CVSS base
5.1
medium
Remediation
The vendor's own words where we have them.
Upgrade Concrete CMS to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.
First 24 hours
Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.
- Identify exposed assets running affected vendor/product/version combinations.
- Prioritize based on EPSS, PoC availability, and external exposure.
- Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.
Affected scope
Vendor, product and version as the advisories word them.
| Vendor | Product | Versions | Status |
|---|---|---|---|
| Concrete CMS | Concrete CMS | 9.2.0 to <= 9.5.2 | Vulnerable |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Attack Complexity
Low
Attack Vector
Network
Privileges Req
High
User Interaction
None
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 5.1 | CVSS 4.0 | medium | — | — | Concrete CMS (CNA) |
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
What this weakness leads to
MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.
CWE-862 · Missing Authorization
- Read Application Data
- Read Files or Directories
- Modify Application Data
- Modify Files or Directories
Mitigation: Divide the software into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
Weakness & attack patterns
- CWE-862
Inferred from the weakness class — not observed against this CVE.
- T1211Exploitation for Defensive Evasion
- T1542.002Pre-OS Boot: Component Firmware
- T1556Modify Authentication Process
Detection
Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.
- Search application, proxy, and WAF logs for requests touching /AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N.
- Prioritize edge telemetry for network-reachable Concrete CMS.
Timeline
What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.
- 2026
Added · CVSS 3.1 5.1 (AV:N)
Sep 11, 2026 · NVD
Initial · CVE published
Sep 11, 2026 · NVD
Added · GHSA-pcwm-p48j-jmfv published (medium)
Sep 11, 2026 · GitHub Security Advisory
CVE published by MITRE.
Sep 11, 2026 · SOCRadar CTI
References
3 on the record
- documentation.concretecms.org/developers/introduction/version-history/953-release-notes
Vendor Advisory
- nvd.nist.gov/vuln/detail/CVE-2026-68535
NVD
- github.com/advisories/GHSA-pcwm-p48j-jmfv
Exploit, Third Party Advisory
Elsewhere on this site
- Concrete CMSevery CVE for this vendor
- Access Controlsame class
- CWE-862other pages naming this weakness
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record1
What should defenders know first?
CVE-2026-68535 is Concrete CMS 9.2.0 to 9.5.2 is vulnerable to Missing authorization in the Concrete CMS Area REST API block-create path letting an editor reference files outside their file-manager permissions, a medium vulnerability affecting Concrete CMS from Concrete CMS. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-68535. Public exploit evidence is: A public PoC is not confirmed from current sources for CVE-2026-68535. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 5.1 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.