CVE-2026-82818: dibo-software diboot Auth Bypass Vulnerability

CVE-2026-82818 Overview

CVE-2026-82818 affects dibo-software diboot version 3.8.0. The flaw resides in the Tenant Resource Assignment Handler exposed through the /api/iam/tenant/resource endpoint. An authenticated remote attacker can manipulate the tenantId parameter to bypass access controls and interact with tenant resources outside their assigned scope. The weakness is categorized as [CWE-266] Incorrect Privilege Assignment. The exploit has been publicly disclosed, and the vendor did not respond to early disclosure attempts. EPSS data indicates a low near-term exploitation probability, though public availability of details increases risk for exposed multi-tenant deployments.

Critical Impact

Authenticated remote attackers can bypass tenant isolation in diboot 3.8.0, compromising confidentiality, integrity, and availability of cross-tenant resources.

Affected Products

• dibo-software diboot 3.8.0
• Component: Tenant Resource Assignment Handler
• Endpoint: /api/iam/tenant/resource

Discovery Timeline

• 2026-08-31 - CVE-2026-82818 published to NVD
• 2026-08-31 - Last updated in NVD database

Technical Details for CVE-2026-82818

Vulnerability Analysis

The vulnerability exists in the identity and access management (IAM) tenant resource assignment logic within diboot 3.8.0. The /api/iam/tenant/resource endpoint accepts a tenantId argument that the application uses to scope resource assignments. The handler does not sufficiently verify that the authenticated caller has authority over the supplied tenantId. As a result, a low-privileged user in one tenant can submit requests referencing another tenant's identifier and influence resources belonging to that tenant. This breaks the multi-tenant isolation model that diboot enforces at the IAM layer.

Root Cause

The root cause is improper access control mapped to [CWE-266] Incorrect Privilege Assignment. The handler trusts the client-supplied tenantId argument without validating it against the session principal's tenant membership or role. Authorization checks are performed against the endpoint but not against the specific object referenced by tenantId, an object-level authorization gap common in multi-tenant SaaS backends.

Attack Vector

The attack is remotely reachable over the network and requires low privileges. An attacker with a valid low-privileged account submits an HTTP request to /api/iam/tenant/resource and substitutes the tenantId value with the identifier of a target tenant. Because no user interaction is required and the exploit has been publicly disclosed, weaponization is straightforward. Successful exploitation yields limited confidentiality, integrity, and availability impact against resources of unrelated tenants.

No verified proof-of-concept code is included here. Refer to the VulDB CVE-2026-82818 entry and the VulDB Vulnerability #397235 record for technical disclosure details.

Detection Methods for CVE-2026-82818

Indicators of Compromise

• Requests to /api/iam/tenant/resource where the tenantId parameter does not match the caller's session tenant claim.
• IAM audit log entries showing tenant resource assignments performed by users lacking tenant-admin roles.
• Unexpected changes to tenant resource ownership or assignments not initiated through standard administrative workflows.

Detection Strategies

• Correlate authenticated session identifiers with tenantId values on the /api/iam/tenant/resource endpoint and alert on mismatches.
• Baseline normal per-user tenant scope and flag deviations where a single account interacts with multiple tenant identifiers.
• Enable verbose logging on the Tenant Resource Assignment Handler to capture request bodies and parameter values for forensic review.

Monitoring Recommendations

• Ingest diboot application and IAM audit logs into a centralized SIEM for continuous review.
• Monitor authorization decisions and rejected requests targeting IAM endpoints for reconnaissance patterns.
• Alert on repeated 200-OK responses to /api/iam/tenant/resource from non-administrative accounts.

How to Mitigate CVE-2026-82818

Immediate Actions Required

• Restrict network exposure of the diboot IAM API to trusted management networks or via VPN until a fix is available.
• Audit existing tenant resource assignments in diboot 3.8.0 to identify unauthorized cross-tenant changes.
• Rotate credentials for accounts that may have been used to trigger the vulnerable endpoint.
• Enforce least-privilege role assignments and remove unnecessary low-privileged accounts from production tenants.

Patch Information

No vendor patch is currently referenced. The vendor was contacted early about this disclosure but did not respond. Monitor the dibo-software diboot project for future security releases and apply updates as soon as they are published.

Workarounds

• Deploy an API gateway or reverse proxy rule that validates the tenantId parameter against the authenticated session's tenant claim before forwarding requests.
• Apply a Web Application Firewall (WAF) rule to block requests to /api/iam/tenant/resource from non-administrative user roles.
• Segment diboot deployments so that each tenant runs in an isolated instance, reducing blast radius until a patch is released.