medium·Web Vulnerabilities·Updated Aug 19, 2026

CVE-2026-8237 Scanner

CVE-2026-8237 Scanner - Insecure Direct Object References (IDOR) vulnerability in Concrete CMS

Est. Time~10 seconds
Scan TypeGroup Scan
Targetsdomain, subdomain, ipv4
CostFree
0
Times Used
by S4E users
0
Assets Scanned
domains & IPs
0
Vulnerabilities Found
confirmed findings
References
CVECVE-2026-8237
6.3
CVSSmedium
Exploitable remotely over the internet · no authentication required.

Concrete CMS 9.5.0 and below is vulnerable to IDOR. The `/ccm/frontend/conversations/message_detail` endpoint returns the full content of any conversation message. An unauthenticated attacker can enumerate all conversation messages, including messages from restricted pages, member-only areas, and the moderation queue. File attachments with download URLs are also exposed. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with Vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Eldudareeno for reporting.

Attack Vector
Network
Privileges Req.
None
User Interaction
None
Affected
Concrete CMSby Concrete CMS
5.0
Updated Aug 22, 2026View on NVD →
Detail

Concrete CMS is a popular content management system used by individuals and organizations to build websites and portals. Developed by Concrete CMS, this software is known for its user-friendly interface and flexible features. It is mainly used for managing web content, blog creation, and online communities. Designers, developers, and site builders utilize this platform for its robust capabilities and extendable nature. Companies and freelancers often choose Concrete CMS for its support of customized templates and add-ons. It allows for easy modifications and enhancements which makes it a preferred choice in many sectors.

The Insecure Direct Object References (IDOR) vulnerability in Concrete CMS allows access to restricted conversation messages and file attachments without proper authentication. This vulnerability occurs due to inadequate access control measures in the /ccm/frontend/conversations/message_detail endpoint. Attackers can exploit this flaw to enumerate and access sensitive information that should be protected. The potential to disclose internal communications and attachments presents significant security risks. IDOR issues generally arise when application logic fails to securely check permissions, making them a critical concern for web-based applications like Concrete CMS.

The vulnerability lies in the endpoint /ccm/frontend/conversations/message_detail, specifically associated with the cnvMessageID parameter. It affects versions of Concrete CMS up to and including 9.5.0. By sending crafted requests to this endpoint, attackers can bypass authorization checks and access messages and attachments directly. This flaw indicates that the access control checks are insufficient or improperly implemented, allowing unauthorized users to exploit them. The exposure is critical because sensitive information can be easily obtained from conversation messages and attachments by manipulating this parameter.

Exploiting this vulnerability can result in unauthorized access to confidential communication threads and attachments. Malicious agents could harvest sensitive data, including potentially personal or proprietary information. The leakage of internal conversations could lead to reputational damage or financial loss if exploited in contexts like corporate communication or customer service dialogues. The vulnerability could also be a stepping stone for more sophisticated attacks by providing attackers with valuable information for further exploitation. Organizations using vulnerable versions should prioritize immediate updates to safeguard against potential breaches.

REFERENCES

Solution Advice
  • Update Concrete CMS to a version later than 9.5.0 or to the latest available version.
  • Implement comprehensive access control measures to protect sensitive endpoints.
  • Conduct regular security audits to identify and resolve potential IDOR issues.
  • Ensure proper logging and monitoring to detect unauthorized access attempts promptly.
  • Educate developers on secure coding practices to prevent IDOR and similar vulnerabilities.

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