Critical Veeam Backup & Replication Vulnerability: What Houston Businesses Need to Know

On March 19, 2025, Veeam, a leading provider of backup and recovery software, released a security advisory for a critical vulnerability in their Backup & Replication product. This vulnerability, tracked as CVE-2025-23120, has received a CVSS score of 9.9, indicating its severe nature and potential impact on affected systems.

  The Vulnerability Explained

CVE-2025-23120 is a remote code execution (RCE) vulnerability affecting Veeam Backup & Replication versions 12, 12.1, 12.2, and 12.3 (up to build 12.3.0.310). The vulnerability was discovered and reported by security researcher Piotr Bazydlo of watchTowr Labs.

At its core, the issue stems from a flawed deserialization handling mechanism in Veeam’s software. According to watchTowr Labs’ analysis, Veeam Backup & Replication follows the industry standard of controlling which classes can be deserialized by implementing an allow-list. However, the implementation is problematic because one of the allowed classes leads to inner deserialization, which relies on a block-list instead of an allow-list approach. This leaves the door open for attackers to bypass Veeam’s security controls.

  Who Is Affected?

The vulnerability specifically impacts Veeam Backup & Replication servers that are joined to an organization’s Active Directory domain. While Veeam notes that domain-joined backup servers are against security and compliance best practices, security researchers at Rapid7 believe this is likely a common configuration in many organizations.

  Exploitation Details

The vulnerability can be exploited by authenticated domain users. In practical terms, this means that any employee within your organization who has domain credentials could potentially execute code with system-level privileges on your backup server.

On March 20, 2025, watchTowr Labs released technical details about the vulnerability, including how a proof-of-concept exploit for a previously discovered vulnerability (CVE-2024-40711) can be modified to exploit CVE-2025-23120. This public disclosure increases the risk of exploitation in the wild.

The severity of this vulnerability is particularly concerning considering that backup systems are prime targets for ransomware attacks. Compromising a backup system can allow attackers to delete or encrypt backups before launching their main attack, eliminating the possibility of recovery without paying a ransom.

  Remediation Steps

Veeam has released a patch to address this vulnerability. Organizations using affected versions should take the following steps immediately:

1. Update to Veeam Backup & Replication version 12.3.1 (build 12.3.1.1139), which includes fixes for the vulnerability.
2. Do not delay this update for regular patch cycles – the critical nature of the vulnerability and the availability of technical details warrant immediate action.
3. For organizations unable to update immediately, consider temporarily disconnecting the Backup & Replication server from the domain if possible.
4. Review the principles of least privilege for domain users who might have access to the backup system.
5. Monitor for suspicious activities targeting your backup infrastructure.

  How CinchOps Can Help

At CinchOps, we understand the critical nature of backup systems and the devastating impact that compromised backups can have on business continuity. Our managed security services can help your organization:

1. Rapid Vulnerability Assessment: We can quickly identify if your Veeam infrastructure is vulnerable and prioritize remediation.
2. Patch Management: Our team can help implement security patches with minimal disruption to your backup operations.
3. Security Best Practices: We’ll help you implement security best practices for your backup infrastructure, including proper network segmentation and adherence to the principle of least privilege.
4. Continuous Monitoring: Our 24/7 security monitoring can detect and alert on suspicious activities targeting your backup systems.
5. Backup Security Strategy: We can develop a comprehensive security strategy for your backup infrastructure that aligns with industry best practices.

Discover more about our enterprise-grade and business protecting cybersecurity services on our Cybersecurity page.

Don’t wait until your backup systems become the target of an attack. Contact CinchOps today to ensure your critical data protection infrastructure remains secure against emerging threats like CVE-2025-23120.

 

FREE SECURITY ASSESSMENT