CVE-2026-10269: Host Header Authorization Bypass in Decolua 9router

Technical summary

CVE-2026-10269 is an improper authorization vulnerability affecting the isAuthenticated function in src/dashboardGuard.js of decolua 9router. The vulnerability stems from insufficient validation of the Host HTTP header, enabling an authenticated attacker to bypass authorization checks. The issue is classified under CWE-266 (Incorrect Privilege Assignment) and CWE-285 (Improper Authorization), indicating both privilege escalation and authorization logic defects. The CVSS 3.1 score of 6.3 (Medium) reflects the requirement for prior authentication, though the impact spans confidentiality, integrity, and availability.

Business impact

An authenticated attacker exploiting this vulnerability could gain unauthorized access to sensitive dashboard functions or data intended to be restricted by role-based controls. While the attack requires valid credentials, the ability to bypass Host-based authorization checks could allow lateral movement within the application, unauthorized data access, or modification of system settings. For organizations running decolua 9router in production environments, this represents a privilege escalation risk that could lead to unauthorized administrative actions or data breach scenarios.

Affected systems

Decolua 9router versions up to and including 0.4.0 are vulnerable. The affected component is the HTTP Header Handler responsible for authentication decisions. Version 0.4.1 and later contain the security fix. Organizations should inventory all instances of decolua 9router and verify current version numbers to determine exposure.

Exploitability

Exploitation requires an attacker to have valid authentication credentials and network access to the affected application. Once authenticated, the attacker can craft requests with a manipulated Host header to circumvent authorization controls. The attack vector is network-based and does not require user interaction or elevated privileges beyond standard authentication. However, the requirement for prior authentication does reduce the overall attack surface compared to pre-authentication vulnerabilities.

Remediation

Upgrade decolua 9router to version 0.4.1 or later. The patch is identified by commit hash 428e2c045cb9c0eb8080e8b580471a9c2eaa95ca. Verify the upgrade against the official vendor advisory to confirm the correct patch application. Test authorization enforcement in your environment post-upgrade to ensure proper function of Host-based access controls.

Patch guidance

Update decolua 9router components to version 0.4.1 as confirmed in the official release notes or vendor advisory. Prioritize this update for systems in production or handling sensitive data. Consider staging the update in a test environment first to validate that dashboard authorization functionality operates correctly and that no downstream dependencies are affected. Monitor upgrade logs for any initialization errors related to the HTTP header handler.

Detection guidance

Monitor HTTP requests to the dashboard or authentication endpoints for suspicious Host header values that deviate from expected internal hostnames or IP addresses. Log authentication bypass attempts or unexpected authorization failures following successful login. Check for access to administrative functions or restricted resources by users whose roles do not normally permit such access. Review the dashboardGuard.js component logs if available to identify anomalous authorization decisions, particularly those correlated with non-standard Host headers.

Why prioritize this

Although this vulnerability carries a CVSS score of 6.3 (Medium severity), it warrants prioritization for organizations where decolua 9router controls access to critical systems or data. The combination of a straightforward exploitation method and potential for privilege escalation or lateral movement makes it a moderate business risk. The fact that a simple patch to version 0.4.1 exists with no reported breaking changes supports rapid remediation.

Risk score, explained

The CVSS 3.1 score of 6.3 reflects a Medium severity rating driven by the following factors: Attack Vector (Network), Access Complexity (Low), and Privilege Required (Low) indicate a readily exploitable flaw; however, the requirement for prior authentication limits the overall risk. The impact on Confidentiality, Integrity, and Availability (all Low) suggests localized compromise rather than catastrophic failure. The score does not account for business context; organizations with strict role-based access requirements or highly privileged user roles may experience amplified risk and should treat this vulnerability accordingly.

Frequently asked questions