What is CVE-2026-21666?

CVE-2026-21666 is a critical-severity vulnerability in Veeam Backup And Replication, classified under Improper Access Control. CVSS score: 9.9/10. Published 2026-03-12.

How severe is CVE-2026-21666?

Critical severity. CVSS v3 base score is 9.9 out of 10.

Vulnerability in Veeam Backup And Replication

CVE-2026-21666

A vulnerability allowing an authenticated domain user to perform remote code execution (RCE) on the Backup Server.

EPSS: 0.011 (62.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

Affected products

Veeam Backup And Replication — versions 12.3.2
Veeam Veeam_backup_\&_replication

Weakness classification (CWE)

CWE-284 — Improper Access Control

References

support@hackerone.com (Vendor Advisory)

Frequently asked questions

What is CVE-2026-21666?: CVE-2026-21666 is a critical-severity vulnerability in Veeam Backup And Replication, classified under Improper Access Control. CVSS score: 9.9/10. Published 2026-03-12.
How severe is CVE-2026-21666?: Critical severity. CVSS v3 base score is 9.9 out of 10.