CVE-2026-21666
Received Received - Intake
Authenticated Remote Code Execution Vulnerability in Backup Server

Publication date: 2026-03-12

Last updated on: 2026-03-31

Assigner: HackerOne

Description
A vulnerability allowing an authenticated domain user to perform remote code execution (RCE) on the Backup Server.
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Meta Information
Published
2026-03-12
Last Modified
2026-03-31
Generated
2026-06-16
AI Q&A
2026-03-12
EPSS Evaluated
2026-06-15
NVD
CVE-2026-21666
EUVD
EUVD-2026-11574
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
veeam veeam_backup_&_replication From 12.0.0.1402 (inc) to 12.3.2.4465 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-284 The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
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Executive Summary

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.

Impact Analysis

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.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

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.

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