CVE-2026-12686: Authorization Bypass Vulnerability

CVE-2026-12686 Overview

CVE-2026-12686 is a cross-tenant authorization bypass affecting the ADISSS Biloop application. An authenticated user can manipulate the company ID parameter in a POST request to the backend and access data belonging to other tenants hosted in the same subdomain environment. The application fails to verify that the requested company ID matches the authenticated session, resulting in an Insecure Direct Object Reference [CWE-639]. Successful exploitation grants unauthorized access to sensitive customer information, including billing data, and enables unauthorized modification of third-party data.

Critical Impact
An authenticated tenant can read and modify data belonging to other tenants sharing the same multi-tenant environment, breaking tenant isolation.

Affected Products

ADISSS Biloop application (multi-tenant SaaS backend)
Any tenant hosted within the shared subdomain environment
Customer billing and third-party data records exposed through the vulnerable endpoint

Discovery Timeline

2026-07-06 - CVE-2026-12686 published to NVD
2026-07-06 - Last updated in NVD database

Technical Details for CVE-2026-12686

Vulnerability Analysis

The vulnerability is a broken access control flaw in the multi-tenant authorization model of ADISSS Biloop. Backend POST endpoints accept a client-supplied company ID identifying the tenant scope for the requested operation. The server processes the request based on that parameter without confirming that the authenticated session is entitled to act on the specified company. Any authenticated user can substitute another tenant's identifier and receive or modify data belonging to that tenant. The flaw enables both horizontal privilege escalation across tenants and unauthorized disclosure of billing and customer records.

Root Cause

The root cause is an Insecure Direct Object Reference [CWE-639]. The application trusts the company ID supplied in the request body rather than deriving tenant scope from the authenticated session or enforcing a server-side authorization check that maps the session to allowed tenant identifiers. Authentication is enforced, but authorization is not.

Attack Vector

Exploitation requires only low-privilege authenticated access to the platform and network reachability to the backend. An attacker logs in with a valid account, intercepts a legitimate POST request, and modifies the company ID field to reference another tenant. Because no cross-check is performed between the session and the target company, the backend returns or updates data owned by the victim tenant. No user interaction from the victim is required.

No verified exploit code is publicly available. See the INCIBE Security Notice for the vendor coordinated advisory.

Detection Methods for CVE-2026-12686

Indicators of Compromise

POST requests where the authenticated user's session identity does not correspond to the company ID parameter transmitted in the body.
Access patterns in which a single account queries or modifies records across multiple distinct company IDs within a short window.
Unexpected reads or writes against billing tables associated with tenants that the requesting user does not own.

Detection Strategies

Correlate application authentication logs with backend request logs to flag mismatches between the session's tenant binding and the company ID parameter.
Baseline normal per-user tenant access and alert on deviations, particularly enumeration of sequential or high-value company IDs.
Implement server-side audit logging for every POST endpoint that accepts a tenant identifier, capturing session ID, user ID, and requested company ID for offline analysis.

Monitoring Recommendations

Monitor web application firewall (WAF) and reverse proxy logs for high-frequency variations of the company ID parameter from a single session.
Alert on anomalous volumes of successful requests returning data from multiple tenants to one authenticated principal.
Review database access logs for cross-tenant SELECT and UPDATE operations initiated by application service accounts on behalf of a single user session.

How to Mitigate CVE-2026-12686

Immediate Actions Required

Apply the vendor-supplied fix referenced in the INCIBE Security Notice as soon as it is available.
Audit application logs for prior cross-tenant access attempts and notify affected customers if unauthorized access is confirmed.
Rotate credentials and session tokens for any account suspected of abusing the vulnerable endpoint.

Patch Information

Refer to the INCIBE Security Notice for vendor remediation guidance. No public patch identifier or fixed version was listed in the NVD entry at the time of publication.

Workarounds

Enforce server-side authorization checks that derive the tenant scope from the authenticated session and reject any request whose company ID does not match the allowed set.
Deploy a WAF rule or reverse proxy filter that validates the company ID parameter against the session's tenant claim before forwarding requests to the backend.
Restrict access to the affected endpoints to a minimum set of users and monitor them closely until the vendor patch is applied.

bash

# Example reverse-proxy pseudo-rule enforcing session-to-tenant binding
# Reject POST requests where body parameter company_id != session.tenant_id
if ($request_method = POST) {
    if ($arg_company_id != $cookie_tenant_id) {
        return 403;
    }
}