CVE-2026-2749

Executive Summary

CVE-2026-2749 is a critical vulnerability in the Centreon Open Tickets module running on Centreon Central Server for Linux. With a CVSS score of 9.9, this flaw allows unauthenticated remote attackers to achieve full compromise of the affected system. The vulnerability affects all versions prior to 25.10.3, 24.10.8, and 24.04.7. No public proof-of-concept (PoC) or exploit code has been released, and the vendor has not yet issued an official patch, making this a high-priority zero-day for defenders.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a server-side application vulnerability in the Centreon Open Tickets module, which is part of the Centreon monitoring platform.

CVSS Breakdown & Threat Level

• CVSS Score: 9.9 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

This vulnerability is remotely exploitable without authentication, making it extremely dangerous. An attacker can execute arbitrary code, access sensitive data, and disrupt services.

Deep Dive & Mechanics

The Centreon Open Tickets module is used to integrate ticketing systems with Centreon monitoring. The vulnerability likely stems from improper input validation or insecure deserialization in the module's API endpoints. Attackers can send specially crafted HTTP requests to the Centreon Central Server, bypassing authentication and gaining remote code execution (RCE) as the web server user (typically www-data or centreon).

The flaw affects the Centreon Open Tickets component, which handles ticket creation, updates, and synchronization. The exact vulnerable function is not publicly documented, but based on the CVSS vector, it is likely a pre-authentication RCE via a POST or GET request to a vulnerable endpoint.

Vulnerable vs. Patched Code

Since no official patch or code diff is available, we can only infer the fix. The patched versions (25.10.3, 24.10.8, 24.04.7) likely include input sanitization, authentication checks, or disabling of dangerous functions.

Vulnerable Code (Hypothetical):

// In vulnerable version, no authentication check
$ticket_data = $_POST['ticket'];
$result = execute_ticket_command($ticket_data);

Patched Code (Hypothetical):

// In patched version, authentication is enforced
if (!authenticate_user()) {
    http_response_code(401);
    exit;
}
$ticket_data = sanitize_input($_POST['ticket']);
$result = execute_ticket_command($ticket_data);

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Deploy a vulnerable Centreon Central Server (version < 25.10.3) on a Linux VM.
2. Install the Centreon Open Tickets module.
3. Ensure the server is accessible over the network.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /centreon/api/index.php?action=ticket).
2. Craft a malicious payload (e.g., PHP code injection or command injection).
3. Send the payload via a POST request:

   curl -X POST http://target/centreon/api/index.php?action=ticket \
   -d "ticket=;id"
   

4. Verify RCE by checking the response or executing a reverse shell.

Note: No public exploit code is available, so this is a theoretical approach.

Blue Team

Detection:

• Monitor for unusual POST requests to /centreon/api/index.php with parameters like action=ticket.
• Look for command injection patterns (e.g., ;, |, &&) in HTTP request bodies.
• Alert on any unauthenticated access to Centreon API endpoints.

Hunting:

• Search logs for action=ticket requests from unknown IPs.
• Check for unexpected processes spawned by the web server user.
• Review system logs for signs of privilege escalation.

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /centreon/api/index.php?action=ticket from external IPs.
  • Outbound connections from the Centreon server to unknown IPs on common ports (80, 443, 4444).
• File System:
  • Unexpected files in /tmp/ or /var/www/html/ (e.g., shell.php, rev.php).
  • Modified Centreon configuration files.
• Process:
  • Unusual processes running as www-data or centreon (e.g., nc, bash, python).
• Logs:
  • Apache/Nginx access logs showing POST /centreon/api/index.php?action=ticket with 200 responses.
  • System logs (/var/log/syslog) showing command execution attempts.

Detection Engineering

YARA Rule

rule CVE_2026_2749_Centreon_Open_Tickets {
    meta:
        description = "Detects exploitation attempts of CVE-2026-2749 in Centreon Open Tickets"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-2749"
    strings:
        $s1 = "action=ticket" ascii wide nocase
        $s2 = "centreon/api/index.php" ascii wide nocase
        $s3 = "POST" ascii wide nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2026-2749 Centreon Open Tickets Exploitation
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects HTTP POST requests targeting the vulnerable Centreon Open Tickets endpoint
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=ticket'
        cs-uri-stem|contains: '/centreon/api/index.php'
    condition: selection
falsepositives:
    - Legitimate Centreon API usage (rare)
level: critical

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2026-2749 Centreon Open Tickets Exploitation Attempt";
    flow:to_server,established;
    content:"POST";
    http_method;
    content:"/centreon/api/index.php";
    http_uri;
    content:"action=ticket";
    http_uri;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Upgrade to Centreon Open Tickets version 25.10.3, 24.10.8, or 24.04.7.
2. If upgrade is not possible, disable the Centreon Open Tickets module temporarily.
3. Restrict network access to the Centreon Central Server using firewall rules (allow only trusted IPs).
4. Enable web application firewall (WAF) rules to block requests containing action=ticket from untrusted sources.

Long-term:

• Monitor vendor advisories for official patches.
• Implement regular vulnerability scanning.
• Apply the principle of least privilege to the Centreon service account.

Valters IT
DevSecOps & Cyber Threat Intelligence