CVE-2026-90449 Overview
CVE-2026-90449 is a missing authentication vulnerability [CWE-306] affecting a reverse proxy component in an operational technology (OT) gateway product. When a specific authentication mode is configured, the reverse proxy forwards requests for a bundled third-party administrative interface without applying the gateway's own authentication layer. Access control is delegated entirely to the downstream interface's login mechanism. Because that administrative interface manages the credential store used to gate every other service in the deployment, any weakness in the bundled interface's authentication can compromise credentials protecting the rest of the environment. The issue was disclosed through a CISA ICS advisory.
Critical Impact
The gateway's authentication requirement is not enforced on requests to a bundled admin interface that controls the central credential store for the deployment.
Affected Products
- Operational technology gateway product referenced in CISA ICS advisory ICSA-26-254-01
- Deployments using the specific authentication mode described in the advisory
- Environments relying on the bundled third-party administrative interface for credential management
Discovery Timeline
- 2026-09-11 - CVE-2026-90449 published to the National Vulnerability Database (NVD)
- 2026-09-18 - Last updated in NVD database
Technical Details for CVE-2026-90449
Vulnerability Analysis
The vulnerability stems from a broken access control chain between the gateway's reverse proxy and a bundled third-party administrative interface. In the affected configuration mode, the reverse proxy passes requests targeting the admin interface directly to the downstream service. The gateway's own authentication layer is skipped for this path.
The admin interface controls the credential store that protects every other service in the deployment. As a result, the security posture of the entire gateway depends on the strength of a single downstream login mechanism. Any authentication weakness in the bundled interface, such as default credentials, weak session handling, or a bypass flaw, propagates to the credential store and every dependent service.
Root Cause
The root cause is a design flaw classified under [CWE-306] (Missing Authentication for a Critical Function). The reverse proxy conditionally omits the gateway's authentication requirement based on the selected authentication mode. This creates an implicit trust boundary that assumes the downstream interface enforces equivalent controls.
Attack Vector
An unauthenticated network attacker can reach the bundled administrative interface through the reverse proxy without traversing the gateway's authentication layer. Exploitation requires network access to the gateway and knowledge that the vulnerable authentication mode is in use. If the downstream interface has any authentication weakness, the attacker can reach the credential store and pivot to services gated by those credentials.
No verified public exploit code is available. See the CISA ICS Security Advisory for vendor-specific technical details.
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Stop Identity AttacksDetection Methods for CVE-2026-90449
Indicators of Compromise
- Unexpected HTTP requests to the bundled admin interface path proxied through the gateway from external or untrusted networks
- Successful admin interface logins that were not preceded by gateway-level authentication events
- Credential store modifications, new service accounts, or exported credentials that do not correlate with change tickets
Detection Strategies
- Correlate reverse proxy access logs with gateway authentication logs to identify admin interface sessions with no matching gateway auth event
- Alert on any access to the bundled admin interface originating from source addresses outside a defined management network
- Baseline normal admin interface usage patterns and flag deviations in request rate, source, or user agent
Monitoring Recommendations
- Enable verbose logging on the reverse proxy for all requests matching the admin interface URI
- Forward gateway, reverse proxy, and admin interface logs to a central SIEM for cross-source correlation
- Monitor the credential store for unauthorized read or write operations and configuration changes
How to Mitigate CVE-2026-90449
Immediate Actions Required
- Review the gateway configuration and identify deployments using the vulnerable authentication mode described in ICSA-26-254-01
- Restrict network access to the gateway's admin interface using firewall rules or a management VLAN
- Rotate credentials stored in the bundled admin interface if unauthorized access cannot be ruled out
Patch Information
Refer to the CISA ICS Security Advisory for vendor patch availability and version guidance. No vendor advisory URL is included in the enriched CVE data at time of publication.
Workarounds
- Switch to an authentication mode that enforces the gateway's own authentication requirement in front of the admin interface
- Place the gateway behind a network segmentation boundary that only permits admin interface access from trusted jump hosts
- Enforce strong, unique credentials and multi-factor authentication on the bundled admin interface where supported
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
