CRITICAL CVSS 9.9
Published: 2026-03-11

CVE-2026-27591

wintercms winter Security Advisory (CVE-2026-27591)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-27591 impacting wintercms winter. Evaluated with CVSS Base Score of 9.9 (CRITICAL).

Original NVD Description

Source: NIST NVD
Winter is a free, open-source content management system (CMS) based on the Laravel PHP framework. Prior to 1.0.477, 1.1.12, and 1.2.12, Winter CMS allowed authenticated backend users to escalate their accounts level of access to the system by modifying the roles / permissions assigned to their account through specially crafted requests to the backend while logged in. To actively exploit this security issue, an attacker would need access to the Backend with a user account with any level of access. This vulnerability is fixed in 1.0.477, 1.1.12, and 1.2.12.

📊 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
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
High (C:H)
Total information disclosure
Integrity
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product wintercms / winter
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-2026-27591 impacting wintercms winter.

⚡ Nuclei Detection Template (YAML) cve-2026-27591.yaml
id: cve-2026-27591

info:
  name: wintercms winter - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: critical
  description: |
    Automated signature & scanner for CVE-2026-27591 affecting wintercms winter.
    Evaluation: Winter is a free, open-source content management system (CMS) based on the Laravel PHP framework. Prior to 1.0.477, 1.1.12, and 1.2.12, Winter CMS all...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-27591
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 9.9
    cve-id: CVE-2026-27591
    cwe-id: CWE-284
  tags: cve,cve-2026-27591,wintercms,winter,critical

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "winter"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-27591.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-27591
# Target: wintercms winter | CVSS: 9.9 (CRITICAL)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-27591 (wintercms winter)...")
    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 wintercms winter 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-2026-27591.sh
# Recommended Remediation & Patching Commands for CVE-2026-27591
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install winter 2>/dev/null || \
sudo dnf upgrade winter 2>/dev/null || \
sudo yum update winter

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

# 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-2026-27591 in wintercms winter?

Review vendor-specific security notices and update wintercms winter 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-2026-27591?

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-2026-27591?

CVE-2026-27591 is classified with a CVSS 3.1 Base Score of 9.9 (CRITICAL). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
9.9
CRITICAL SEVERITY
CVE ID CVE-2026-27591
Weakness CWE-284
Vendor wintercms
Product winter
Published 2026-03-11
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H