Quick answers
- Is CVE-2026-61399 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-61399 being exploited in the wild.
- How severe is CVE-2026-61399?
- Medium severity, with a CVSS score of 4.8, published 21 August 2026.
- Which products and versions are affected?
- Apache Cloudstack 4.20.0.0 to 4.20.3.0, 4.21.0.0 to 4.22.1.0.
- Is there a fix for CVE-2026-61399?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-61399 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-61399?
- Check whether you run Apache Cloudstack at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
An Improper Encoding or Escaping of Output vulnerability (CWE-116) exists in Apache CloudStack's UI when using the Lock User functionality. The vulnerability stems from insufficient output encoding/escaping in the web interface, potentially allowing stored or reflected XSS attacks. The attack vector is network-accessible via the CloudStack UI. Exploitation requires network access to the CloudStack management interface; depending on the context, user interaction or prior authentication may be required. An attacker can inject malicious scripts that execute in the context of authenticated users' browsers. Patches are available in versions 4.20.3.1, 4.22.1.1, and later.
Affected products
- Apache CloudStack 4.20.0.0 to 4.20.3.0, 4.21.0.0 to 4.22.1.0
Timeline
- 2026-08-21: disclosed