CVE-2026-21666
Authenticated Remote Code Execution Vulnerability in Backup Server
Publication date: 2026-03-12
Last updated on: 2026-03-31
Assigner: HackerOne
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| veeam | veeam_backup_&_replication | From 12.0.0.1402 (inc) to 12.3.2.4465 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-284 | The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
CVE-2026-21666 is a critical security vulnerability found in Veeam Backup & Replication versions 12.3.2.4165 and earlier 12.x builds. It allows an authenticated domain user to execute remote code on the Backup Server. This means that someone with valid domain credentials can run arbitrary code remotely on the server responsible for backups.
The vulnerability has a very high severity score of 9.9 out of 10 according to CVSS v3.1, indicating it is easy to exploit over the network with low complexity and no user interaction required. It impacts confidentiality, integrity, and availability of the system.
How can this vulnerability impact me? :
This vulnerability can have severe impacts including unauthorized remote code execution on your Backup Server by an authenticated domain user. This could lead to full compromise of the backup infrastructure.
- Loss of confidentiality due to potential data exposure.
- Loss of integrity as attackers could modify backup data or system configurations.
- Loss of availability if the backup server is disrupted or taken offline.
Overall, this vulnerability could allow attackers to control backup operations, potentially leading to data loss, ransomware attacks, or disruption of disaster recovery processes.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate CVE-2026-21666, customers are strongly advised to update Veeam Backup & Replication to version 12.3.2.4465 immediately.
This update resolves the critical remote code execution vulnerability and includes fixes for multiple other critical and high-severity issues.