MEDIUM CVSS 4.3
Published: 2026-05-21

CVE-2026-8327

concretecms concrete_cms Security Advisory (CVE-2026-8327)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-8327 impacting concretecms concrete_cms. Evaluated with CVSS Base Score of 4.3 (MEDIUM).

Original NVD Description

Source: NIST NVD
Concrete CMS below 9.5.0 and below is vulnerable to password change without reauthorization and session-hardening bypass. The user-profile edit controller passes the entire raw POST array to UserInfo::update() without field whitelisting resulting in password change without requiring the current password  and also resulting in registered users able to disable the per-user-IP-pinning in the session validator which is meant to detect hijacking.  The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks 0x4c616e for reporting.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
Low (PR:L)
Standard user access required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
None (C:N)
No data confidentiality impact
Integrity
Low (I:L)
Partial data modification possible
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product concretecms / concrete_cms
Affected Versions *
Weakness Enumeration CWE-269

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-8327 impacting concretecms concrete_cms.

⚡ Nuclei Detection Template (YAML) cve-2026-8327.yaml
id: cve-2026-8327

info:
  name: concretecms concrete_cms - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-8327 affecting concretecms concrete_cms.
    Evaluation: Concrete CMS below 9.5.0 and below is vulnerable to password change without reauthorization and session-hardening bypass. The user-profile edit contro...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-8327
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
    cvss-score: 4.3
    cve-id: CVE-2026-8327
    cwe-id: CWE-269
  tags: cve,cve-2026-8327,concretecms,concrete_cms,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "concrete_cms"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-8327.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-8327
# Target: concretecms concrete_cms | CVSS: 4.3 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-8327 (concretecms concrete_cms)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against concretecms concrete_cms scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-8327.sh
# Recommended Remediation & Patching Commands for CVE-2026-8327
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install concrete_cms 2>/dev/null || \
sudo dnf upgrade concrete_cms 2>/dev/null || \
sudo yum update concrete_cms

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i concrete_cms 2>/dev/null || rpm -qa | grep -i concrete_cms

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

🔗 Verified Technical References

Authorities
  • No records filed in this category.
Distributions
  • No records filed in this category.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-8327 in concretecms concrete_cms?

Review vendor-specific security notices and update concretecms concrete_cms packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-8327?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-8327?

CVE-2026-8327 is classified with a CVSS 3.1 Base Score of 4.3 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
4.3
MEDIUM SEVERITY
CVE ID CVE-2026-8327
Weakness CWE-269
Vendor concretecms
Product concrete_cms
Published 2026-05-21
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N