CVE-2025-26819

Remediation/Mitigation Strategy for CVE-2025-26819 (Monero HTTP Server Connection Limit Vulnerability)

1. Vulnerability Description:

  • CVE ID: CVE-2025-26819
  • Affected Software: Monero (versions up to and including 0.18.3.4 before commit ec74ff4)
  • Description: Monero through 0.18.3.4 before ec74ff4 does not have response limits on HTTP server connections. This lack of response limits allows an attacker to potentially exhaust server resources by sending a large number of requests, leading to a Denial of Service (DoS) condition. The vulnerability stems from the Monero HTTP server not properly limiting the number of connections or the amount of data sent in response to requests.

2. Severity Assessment:

  • CVSS v3.x Score: 8.6 (High)
  • CVSS Vector: Based on the provided data, the CVSS vector is likely AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (Network, Low Attack Complexity, No Privileges Required, No User Interaction, Unchanged Scope, No Confidentiality Impact, No Integrity Impact, High Availability Impact)
  • Explanation: This vulnerability is rated high because it allows a remote, unauthenticated attacker to cause a Denial of Service (DoS). The attack is easily executed (low attack complexity) and does not require any user interaction. The primary impact is on availability, making the Monero node inaccessible to legitimate users.

3. Known Exploits:

  • While the provided data doesn’t explicitly list known exploits, the vulnerability’s nature (DoS due to missing response limits) makes exploitation straightforward. An attacker can simply flood the Monero node’s HTTP server with a large number of requests.
  • Exploit Scenario: An attacker could use a simple script (e.g., using curl, wget, or Python’s requests library) to repeatedly send requests to the Monero HTTP server. Without proper rate limiting or connection management, the server’s resources (CPU, memory, network bandwidth) would be consumed, causing it to slow down or become unresponsive.

4. Remediation/Mitigation Strategies:

  • Primary Mitigation: Upgrade to a Fixed Version:

    • The most effective solution is to upgrade Monero to a version containing the fix (commit ec74ff4 or later). Check the official Monero website (getmonero.org) for the latest stable release. Follow the official upgrade instructions to ensure a smooth transition.

  • Secondary Mitigations (if immediate upgrade is not possible): These are temporary measures and should be used until a proper upgrade can be performed.

    • Firewall/Network Security Controls:

      • Rate Limiting: Implement rate limiting on the firewall or network device that protects the Monero node. This will restrict the number of connections or requests allowed from a single IP address within a given timeframe. This can help prevent attackers from overwhelming the server.
      • Connection Limits: Configure the firewall to limit the total number of concurrent connections to the Monero node’s HTTP port.
      • Geo-Blocking (if applicable): If the Monero node primarily serves a specific geographic region, consider blocking connections from other regions to reduce potential attack surface.
      • Web Application Firewall (WAF) (if applicable): If a WAF is in use, configure rules to detect and block suspicious traffic patterns indicative of a DoS attack.

    • Monero Configuration (Limited Effectiveness):

      • Review and Harden Monero Configuration: While Monero’s configuration options might not directly address the lack of response limits, review the configuration for any settings that could improve overall performance and security (e.g., enabling TLS, setting appropriate log levels).
      • Monitor System Resources: Closely monitor the Monero node’s CPU usage, memory usage, network traffic, and disk I/O. Set up alerts to notify administrators if resources are being exhausted. This helps detect a DoS attack in progress.

5. Implementation Steps:

  1. Identify Monero Version: Determine the currently installed version of Monero on each affected node.
  2. Plan Upgrade: Schedule a maintenance window for upgrading Monero. Ensure you have a backup of the Monero blockchain data before upgrading.
  3. Upgrade Monero: Follow the official Monero upgrade instructions to upgrade to the latest stable version or a version that includes the fix for CVE-2025-26819.
  4. Verify Upgrade: After the upgrade, verify that Monero is running correctly and that the vulnerability is no longer present.
  5. Implement Secondary Mitigations (if needed): If a full upgrade is not immediately possible, implement the secondary mitigation strategies (firewall rate limiting, connection limits, etc.) as described above.
  6. Monitoring: Continuously monitor the Monero node for any signs of a DoS attack.
  7. Testing: Consider performing penetration testing or vulnerability scanning to verify the effectiveness of the implemented mitigations.

6. Communication:

  • Inform Stakeholders: Communicate the vulnerability and the planned remediation steps to all relevant stakeholders (e.g., users, administrators, management).
  • Provide Timely Updates: Keep stakeholders informed of the progress of the remediation efforts.

7. Rollback Plan:

  • Before upgrading, create a complete backup of the Monero node’s data and configuration.
  • Have a documented procedure for reverting to the previous Monero version in case the upgrade fails or introduces new issues.

Important Considerations:

  • Stay Informed: Continuously monitor security advisories and vulnerability databases for new threats and updates related to Monero and other software used in your environment.
  • Regular Updates: Implement a regular update schedule for Monero and all other software to ensure that you have the latest security patches.
  • Security Best Practices: Follow security best practices for securing Monero nodes and other systems in your environment.

Assigner

Date

  • Published Date: 2025-02-15 00:15:29
  • Updated Date: 2025-02-15 00:15:29

More Details

CVE-2025-26819