IDOR Vulnerability in Concrete CMS by Concrete5
CVE-2026-8239

6.3MEDIUM

Key Information:

Vendor

Concrete Cms

Status
Concrete Cms
Vendor
CVE Published:
21 May 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-8239?

Concrete CMS versions 9.5.0 and earlier are susceptible to an Insecure Direct Object Reference (IDOR) vulnerability. The '/ccm/frontend/conversations/get_rating' endpoint allows unauthorized users to confirm the existence of any message's ID and retrieve its rating score. This exposes sensitive information and can lead to potential abuse of the system. It is crucial for users to implement necessary security measures to mitigate this risk.

Affected Version(s)

Concrete CMS 5.0 <= 9.5.0

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-8239
Created by aj2108

References

https://documentation.concretecms.org/9-x/developers/intr...
release-notes

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Tristan Madani
.