How severe is CVE-2026-21666?

CVE-2026-21666 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-21666 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21666?

CVE-2026-21666 affects Veeam Veeam Backup & Replication. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21666?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-21666 have an EU (EUVD) identifier?

Yes. CVE-2026-21666 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-11574.

When was CVE-2026-21666 published?

CVE-2026-21666 was published on 2026-03-12 and last updated on 2026-06-17.

CVE-2026-21666

CVE-2026-21666 is a critical-severity vulnerability in Veeam Veeam Backup & Replication with a CVSS 3.x base score of 9.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-284.

Key facts

Severity: Critical (CVSS 3.x base score 9.9)
EPSS exploit prediction: 1% (62nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-11574
Weakness: CWE-284
Affected product: Veeam Veeam Backup & Replication
Published: 2026-03-12
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is CVE-2026-21666?: A vulnerability allowing an authenticated domain user to perform remote code execution (RCE) on the Backup Server.
How severe is CVE-2026-21666?: CVE-2026-21666 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-21666 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21666?: CVE-2026-21666 affects Veeam Veeam Backup & Replication. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21666?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-21666 have an EU (EUVD) identifier?: Yes. CVE-2026-21666 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-11574.
When was CVE-2026-21666 published?: CVE-2026-21666 was published on 2026-03-12 and last updated on 2026-06-17.

References

https://www.veeam.com/kb4830

Affected products (1)

cpe:2.3:a:veeam:veeam_backup_\&_replication:*:*:*:*:*:*:*:*

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