HIGH CVSS 8.1
Published: 2026-04-21

CVE-2026-40497

freescout freescout Security Advisory (CVE-2026-40497)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-40497 impacting freescout freescout. Evaluated with CVSS Base Score of 8.1 (HIGH).

Original NVD Description

Source: NIST NVD
FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.213, FreeScout's `Helper::stripDangerousTags()` removes `<script>`, `<form>`, `<iframe>`, `<object>` but does NOT strip `<style>` tags. The mailbox signature field is saved via POST /mailbox/settings/{id} and later rendered unescaped via `{!! $conversation->getSignatureProcessed([], true) !!}` in conversation views. CSP allows `style-src * 'self' 'unsafe-inline'`, so injected inline styles execute freely. An attacker with access to mailbox settings (admin or agent with mailbox permission) can inject CSS attribute selectors to exfiltrate the CSRF token of any agent/admin who views a conversation in that mailbox. With the CSRF token, the attacker can perform any state-changing action as the victim (create admin accounts, change email/password, etc.) — privilege escalation from agent to admin. This is the result of an incomplete fix of GHSA-jqjf-f566-485j. That advisory reported XSS via mailbox signature. The fix applied `Helper::stripDangerousTags()` to the signature before saving. However, `stripDangerousTags()` only removes `script`, `form`, `iframe`, and `object` tags — it does NOT strip `<style>` tags, leaving CSS injection possible. Version 1.8.213 contains an updated fix.

📊 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
High (PR:H)
Administrative credentials required
User Interaction
Required (UI:R)
User must click or open resource
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
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product freescout / freescout
Affected Versions *
Weakness Enumeration CWE-79

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-2026-40497 impacting freescout freescout.

⚡ Nuclei Detection Template (YAML) cve-2026-40497.yaml
id: cve-2026-40497

info:
  name: freescout freescout - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-40497 affecting freescout freescout.
    Evaluation: FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.213, FreeScout&#x27;s `Helper::stripDangerousTags()` removes `&lt;s...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-40497
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N
    cvss-score: 8.1
    cve-id: CVE-2026-40497
    cwe-id: CWE-79
  tags: cve,cve-2026-40497,freescout,freescout,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "freescout"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-40497.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-40497
# Target: freescout freescout | CVSS: 8.1 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-40497 (freescout freescout)...")
    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 freescout freescout 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-2026-40497.sh
# Recommended Remediation & Patching Commands for CVE-2026-40497
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install freescout 2>/dev/null || \
sudo dnf upgrade freescout 2>/dev/null || \
sudo yum update freescout

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

# 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.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-40497 in freescout freescout?

Review vendor-specific security notices and update freescout freescout 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-2026-40497?

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-2026-40497?

CVE-2026-40497 is classified with a CVSS 3.1 Base Score of 8.1 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
8.1
HIGH SEVERITY
CVE ID CVE-2026-40497
Weakness CWE-79
Vendor freescout
Product freescout
Published 2026-04-21
Vector CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N