MEDIUM CVSS 4.6
Published: 2026-06-01

CVE-2026-45284

nextcloud user_oidc Security Advisory (CVE-2026-45284)
↗ Official NIST NVD Record
Seeking technical exploit breakdowns or verified PoC code for CVE-2026-45284?
🔬 Search Writeups & Exploit Archive →

CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-45284 impacting nextcloud user_oidc. Evaluated with CVSS Base Score of 4.6 (MEDIUM).

Original NVD Description

Source: NIST NVD
Nextcloud is an open source content collaboration platform. From version 1.3.6 to before version 8.4.0, an improper check allowed users that where provided by LDAP to still authenticate towards user OIDC after they where deleted. This issue has been patched in version 8.4.0.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
High (AC:H)
Depends on race conditions or environment
Privileges Required
Low (PR:L)
Standard user access required
User Interaction
Required (UI:R)
User must click or open resource
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
Low (C:L)
Partial information leakage
Integrity
Low (I:L)
Partial data modification possible
Availability
Low (A:L)
Partial service performance degradation

🎯 Affected Versions Matrix

Affected Product nextcloud / user_oidc
Affected Versions *
Weakness Enumeration CWE-284

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-2026-45284 impacting nextcloud user_oidc.

⚡ Nuclei Detection Template (YAML) cve-2026-45284.yaml
id: cve-2026-45284

info:
  name: nextcloud user_oidc - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-45284 affecting nextcloud user_oidc.
    Evaluation: Nextcloud is an open source content collaboration platform. From version 1.3.6 to before version 8.4.0, an improper check allowed users that where pro...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-45284
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L
    cvss-score: 4.6
    cve-id: CVE-2026-45284
    cwe-id: CWE-284
  tags: cve,cve-2026-45284,nextcloud,user_oidc,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "user_oidc"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-45284.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-45284
# Target: nextcloud user_oidc | CVSS: 4.6 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-45284 (nextcloud user_oidc)...")
    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 nextcloud user_oidc 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-2026-45284.sh
# Recommended Remediation & Patching Commands for CVE-2026-45284
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install user_oidc 2>/dev/null || \
sudo dnf upgrade user_oidc 2>/dev/null || \
sudo yum update user_oidc

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

# 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

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-45284 in nextcloud user_oidc?

Review vendor-specific security notices and update nextcloud user_oidc 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-2026-45284?

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-2026-45284?

CVE-2026-45284 is classified with a CVSS 3.1 Base Score of 4.6 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
4.6
MEDIUM SEVERITY
CVE ID CVE-2026-45284
Weakness CWE-284
Vendor nextcloud
Product user_oidc
Published 2026-06-01
Vector CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L