External risk intelligence

Apache CloudStack Instance Reset Password Encoding Flaw

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-61398

Apache CloudStack is a cloud computing platform designed to manage and orchestrate large networks of virtual machines. Its UI and management interfaces are commonly deployed as web-based portals that are network-accessible for administration, making them likely to be exposed as an edge or management service in many infrastructure deployments.

Apache Cloudstack

4.15.1.0 to before 4.20.3.14.21.0.0 to before 4.22.1.1

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in the Apache CloudStack user interface related to its password reset function. This flaw could allow for unauthorized access and modification of data within affected systems, impacting the integrity and confidentiality of cloud environments.

Password reset flaw in CloudStack UI.
Protects cloud data and access controls.
Verify CloudStack relevance and exposure.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by leveraging the "Instance Reset Password" feature within Apache CloudStack's user interface. This could allow them to manipulate how data is displayed, potentially leading to the disclosure of sensitive information or unauthorized modifications.

No authentication or special access needed.
Triggered via the Instance Reset Password function.
Risk of sensitive data exposure or modification.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to compromise sensitive system data or user data when the Instance Reset Password functionality is used within Apache CloudStack's UI.

System configuration data at risk.
Exposure through a vulnerable UI endpoint.
Unauthorized access to internal system details.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in Apache CloudStack's UI, specifically affecting the Instance Reset Password functionality, likely requires coordination between the platform or infrastructure team managing CloudStack deployments and the security team responsible for monitoring and validating exposure. The initial step should be to identify all deployed instances of the affected versions, determine their network accessibility, and confirm business criticality before planning remediation.

Platform owners to verify deployment scope.
Confirm instance reachability and business criticality.
Plan and coordinate remediation efforts.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is Apache CloudStack?

Apache CloudStack is an open-source cloud computing software platform used by organizations to build, deploy, and manage large-scale virtual machine infrastructure. It provides a comprehensive management interface that acts as the control plane for cloud resources, allowing administrators to orchestrate virtual networking, storage, and compute instances through a web-based dashboard.

What does CWE-116 mean for CVE-2026-61398?

CVE-2026-61398 involves a weakness class known as CWE-116, which is Improper Encoding or Escaping of Output. This means the software fails to correctly process special characters when displaying data. In this specific case, the UI does not properly sanitize information related to the Instance Reset Password feature, potentially allowing that data to be misinterpreted or manipulated by the system.

How is this vulnerability triggered in CloudStack?

The flaw is triggered specifically through the Instance Reset Password functionality within the web user interface. It is important to note that the vulnerability does not require an attacker to have prior authentication or special permissions to attempt an interaction. Simply navigating to or utilizing this specific password reset interface endpoint is the mechanism that exposes the underlying encoding flaw.

Is my Apache CloudStack instance at risk?

Halo Surface Signal indicates that Apache CloudStack interfaces are often deployed as web-based portals accessible over a network for administration. If your management interface is reachable from the internet, it is more likely to be exposed to external threats. You should assess whether your deployment's UI is accessible to unauthorized users or restricted to private, trusted network segments.

What should I do to secure my environment?

Your first step is to audit your infrastructure to identify all running versions of Apache CloudStack. Compare these against the affected version ranges provided in the advisory and prioritize those that are network-accessible. Once identified, plan an upgrade to version 4.20.3.1, 4.22.1.1, or a later release, as these versions contain the necessary fixes to resolve the encoding issue.

References

lists.apache.org/thread/g6cwddtjrwbh1d56wjz4cfp3fzfm4kbc

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.