CVE-2026-61397 Overview
CVE-2026-61397 is an information disclosure vulnerability [CWE-200] in Apache CloudStack's OAuth2 authentication plugin and Google OAuth integration. The flaw exposes sensitive information to unauthorized actors through the OAuth2 authentication flow. Affected versions include Apache CloudStack 4.19.0.0 through 4.20.3.0 and 4.21.0.0 through 4.22.1.0. The Apache CloudStack project has released fixed versions 4.20.3.1 and 4.22.1.1 to address the issue. The vulnerability is remotely exploitable over the network without authentication or user interaction.
Critical Impact
Unauthenticated remote attackers can access sensitive information exposed through the OAuth2 authentication plugin and Google OAuth integration, undermining the confidentiality of CloudStack deployments.
Affected Products
- Apache CloudStack versions 4.19.0.0 through 4.20.3.0
- Apache CloudStack versions 4.21.0.0 through 4.22.1.0
- Deployments using the OAuth2 authentication plugin or Google OAuth integration
Discovery Timeline
- 2026-08-21 - CVE-2026-61397 published to NVD
- 2026-08-27 - Last updated in NVD database
Technical Details for CVE-2026-61397
Vulnerability Analysis
The vulnerability resides in Apache CloudStack's OAuth2 authentication plugin and its Google OAuth integration path. The affected code paths expose sensitive information to unauthorized actors during the OAuth2 authentication flow. An unauthenticated attacker on the network can trigger the exposure without user interaction. The confidentiality impact is high, while integrity and availability are not affected. The issue is tracked under [CWE-200: Exposure of Sensitive Information to an Unauthorized Actor].
Apache CloudStack is widely deployed as an Infrastructure-as-a-Service (IaaS) orchestration platform. OAuth2 is commonly enabled to federate authentication with external identity providers such as Google. Information leaked through this flow can include material used to further compromise identity or account boundaries within the CloudStack management plane.
Root Cause
The root cause is improper handling of sensitive data within the OAuth2 authentication plugin and Google OAuth integration code paths. The plugin returns or otherwise exposes data that should remain confined to authenticated, authorized contexts. Refer to the Apache CloudStack security thread for the vendor's technical description.
Attack Vector
Exploitation occurs over the network against a CloudStack management endpoint exposing OAuth2 authentication. No credentials or user interaction are required. Attackers interact with the OAuth2 authentication endpoints and observe or retrieve data disclosed by the vulnerable plugin. Because CloudStack management interfaces are frequently reachable by administrators over corporate networks or the internet, exposure risk depends on network segmentation.
No public proof-of-concept exploit is available at the time of publication. The EPSS score is 0.336%, indicating a lower near-term probability of observed exploitation. The vulnerability mechanism is described in prose only; consult the vendor advisory for implementation-level details.
Detection Methods for CVE-2026-61397
Indicators of Compromise
- Unexpected requests to CloudStack OAuth2 authentication endpoints from unknown source IPs or user agents.
- Anomalous spikes in OAuth2 callback or authorization requests to the CloudStack management server.
- Successful OAuth2 authentication events without corresponding user activity in downstream systems.
Detection Strategies
- Inspect CloudStack management server access logs for repeated calls to OAuth2 and Google OAuth callback URLs from a single source.
- Correlate CloudStack authentication logs with identity provider logs to identify OAuth flows that lack a matching provider-side session.
- Search HTTP response bodies from OAuth2 endpoints in web application firewall (WAF) or proxy logs for sensitive field patterns.
Monitoring Recommendations
- Forward CloudStack management server logs and reverse proxy logs to a centralized SIEM for retention and correlation.
- Alert on authentication attempts from IP addresses outside expected administrative ranges.
- Track version strings of Apache CloudStack instances against fixed releases 4.20.3.1 and 4.22.1.1.
How to Mitigate CVE-2026-61397
Immediate Actions Required
- Upgrade Apache CloudStack to version 4.20.3.1 or 4.22.1.1 as recommended by the vendor.
- Restrict network access to CloudStack management endpoints to trusted administrative networks and VPNs.
- Rotate OAuth2 client secrets and any tokens that may have transited the affected authentication flow.
Patch Information
Apache has released Apache CloudStack 4.20.3.1 and 4.22.1.1, which remediate this vulnerability. Details are available in the Apache CloudStack announcement thread. Operators running any release in the 4.19.0.0–4.20.3.0 or 4.21.0.0–4.22.1.0 ranges should plan the upgrade immediately.
Workarounds
- Disable the OAuth2 authentication plugin and Google OAuth integration until the patch is applied.
- Enforce network-level access controls that restrict who can reach the OAuth2 endpoints on the CloudStack management server.
- Require multi-factor authentication (MFA) at the upstream identity provider to reduce the value of any exposed data.
# Configuration example: verify installed CloudStack version and disable OAuth2 plugin
rpm -q cloudstack-management || dpkg -l | grep cloudstack-management
# Disable OAuth2 authentication plugin via CloudStack global settings
# (Apply through the admin UI or CloudMonkey CLI)
cloudmonkey update configuration name=oauth2.enabled value=false
cloudmonkey update configuration name=oauth2.plugins.enabled value=""
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
