Vulnerability in Apache Cloudstack

CVE-2026-61399

Improper Encoding or Escaping of Output vulnerability in Apache CloudStack's UI while using Lock User Functionality. This issue affects Apache CloudStack: from 4.20.0.0 through 4.20.3.0 and from 4.21.0.0 through 4.22.1.0. Users are recommended to upgrade to version 4.20.3.1 or 4.22.1.1 or later, which fixes the issue.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.005 (40.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-61399: held from 0.003 to 0.005.

EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-61399?
CVE-2026-61399 is a medium-severity vulnerability in Apache Cloudstack, classified under Improper Encoding or Escaping of Output. CVSS score: 4.8/10. Published 2026-08-21.
How severe is CVE-2026-61399?
Medium severity. CVSS v3 base score is 4.8 out of 10.