CVE-2026-57870: MicroRealEstate Auth Bypass Vulnerability

CVE-2026-57870 Overview

CVE-2026-57870 is a broken object-level access control vulnerability affecting the Template API in MicroRealEstate, an open-source property management platform. Authenticated attackers can retrieve document templates belonging to other organizations without authorization. The flaw stems from missing tenant-scoped authorization checks on template retrieval endpoints. This weakness is classified as [CWE-639] Authorization Bypass Through User-Controlled Key. The issue affects MicroRealEstate versions through 1.0.0-alpha3. Exposed templates may contain sensitive business content, including lease agreements, invoices, and internal correspondence templates used across tenant organizations.

Critical Impact
Authenticated users of one tenant can enumerate and retrieve document templates owned by other organizations, breaching multi-tenant data isolation.

Affected Products

MicroRealEstate through version 1.0.0-alpha3
MicroRealEstate Template API component
Multi-tenant deployments of MicroRealEstate

Discovery Timeline

2026-07-07 - CVE CVE-2026-57870 published to NVD
2026-07-07 - Last updated in NVD database

Technical Details for CVE-2026-57870

Vulnerability Analysis

MicroRealEstate is a self-hosted property management application built on a microservices architecture. The Template API exposes endpoints for managing document templates such as leases, notices, and invoices. In vulnerable releases, the API validates that a caller is authenticated but does not verify that the requested template belongs to the caller's organization.

An authenticated user can issue a request referencing a template identifier that belongs to another organization. The server returns the object without enforcing the tenant boundary. This exposes confidential business content across organizational tenants sharing the same deployment.

The classification [CWE-639] describes Insecure Direct Object Reference (IDOR), where object identifiers are directly usable in requests without server-side authorization checks. The EPSS probability is 0.215%, reflecting low observed exploitation likelihood, but the flaw is trivially reachable by any authenticated user.

Root Cause

The root cause is missing authorization enforcement on the Template API. The service checks authentication tokens but omits an ownership predicate binding templates to their originating organization. Access decisions rely on client-provided identifiers rather than a server-side check comparing the resource's organization to the caller's session-bound organization.

Attack Vector

Exploitation requires low privileges and network access to the Template API. An attacker authenticates as any valid tenant user, enumerates template identifiers, and issues direct requests for templates owned by other organizations. No user interaction is required. The vulnerability manifests over standard HTTPS API calls; consult the The Missing Link Security Advisory for technical details.

Detection Methods for CVE-2026-57870

Indicators of Compromise

Requests to Template API endpoints referencing template identifiers not associated with the caller's organization
Sequential or enumerated identifier patterns in template retrieval requests from a single account
Unexpected cross-organization access entries in application audit logs
High-volume GET requests against template resources originating from a single authenticated session

Detection Strategies

Instrument the Template API to log the calling user's organization alongside the requested template's organization for each request
Alert on any request where the caller's organization differs from the target template's organization
Correlate authentication events with template access to identify low-privilege accounts iterating over template IDs

Monitoring Recommendations

Enable verbose access logging on the MicroRealEstate api and resident gateway services
Forward application logs to a central analytics platform and build detections on cross-tenant object access
Baseline normal template retrieval volume per user account and alert on deviations

How to Mitigate CVE-2026-57870

Immediate Actions Required

Restrict Template API access to trusted internal networks until a fixed release is deployed
Audit historical Template API logs for cross-organization retrievals since deployment
Rotate or review any sensitive content stored in document templates that may have been exposed
Track upstream fixes at the MicroRealEstate GitHub repository

Patch Information

At the time of publication, MicroRealEstate versions through 1.0.0-alpha3 are affected. Consult the The Missing Link Security Advisory and the MicroRealEstate GitHub repository for the latest patched release and remediation guidance.

Workarounds

Deploy a reverse proxy or API gateway rule that inspects template requests and validates the caller's organization claim against the requested resource
Limit MicroRealEstate deployments to single-tenant use until the fix is applied
Restrict user account provisioning and remove unused accounts to reduce the pool of potential attackers

bash

# Example gateway rule concept: deny cross-tenant template access
# Pseudocode for a reverse proxy policy
if request.path matches "/api/v2/templates/*" and
   request.jwt.organization_id != backend.template.organization_id:
    return 403 Forbidden