What is CVE-2026-21671?
A vulnerability allowing an authenticated user with the Backup Administrator role to perform remote code execution (RCE) in high availability (HA) deployments of Veeam Backup & Replication.
The record classifies CVE-2026-21671 under weakness class CWE-94. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs high-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 234 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 9.1 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H - EPSS (FIRST)
- 1.3% probability of exploitation in the next 30 days, higher than 70.7% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 7.4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-03-12, last modified 2026-05-10
Is CVE-2026-21671 being exploited?
It currently carries a trending score of 23 in the Threadlinqs vulnerability feed.
Affected products and versions
- Veeam: Backup & Replication
How to fix CVE-2026-21671
The record marks a vendor fix as available for CVE-2026-21671. Vendor advisory: https://www.veeam.com/kb4831. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-21671
1 tracked threat in the Threadlinqs corpus references CVE-2026-21671, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on .