CVE-2026-21668
Published: 12 March 2026
Summary
CVE-2026-21668 is a high-severity Missing Authorization (CWE-862) vulnerability in Veeam Veeam Backup \& Replication. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 9.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and SI-2 (Flaw Remediation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Enforces approved authorizations for access to system resources, directly preventing authenticated users from bypassing restrictions to manipulate arbitrary files on the backup repository.
Requires timely remediation of identified flaws, such as this missing authorization vulnerability, through patching as recommended in the vendor advisory.
Applies least privilege to authenticated domain users, limiting their access and reducing the impact of the authorization bypass on backup repository files.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Missing authorization enables remote authenticated file read (T1005), deletion (T1070.004), and modification (T1565.001) on the backup repository.
NVD Description
A vulnerability allowing an authenticated domain user to bypass restrictions and manipulate arbitrary files on a Backup Repository.
Deeper analysisAI
CVE-2026-21668 is a vulnerability that allows an authenticated domain user to bypass restrictions and manipulate arbitrary files on a Backup Repository. Published on 2026-03-12, it carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) and is associated with CWE-862 (Missing Authorization). The issue affects Veeam Backup Repository components, as detailed in the vendor's knowledge base.
An attacker with low-privilege access as an authenticated domain user can exploit this vulnerability remotely over the network with low complexity and no user interaction required. Successful exploitation enables manipulation of arbitrary files on the Backup Repository, resulting in high impacts to confidentiality, integrity, and availability, such as unauthorized data access, modification, or deletion.
For mitigation details, refer to the Veeam advisory at https://www.veeam.com/kb4830, which provides guidance on patches and workarounds.
Details
- CWE(s)