CVE-2026-57867: MicroRealEstate Auth Bypass Vulnerability

CVE-2026-57867 Overview

CVE-2026-57867 is an authentication bypass vulnerability in MicroRealEstate, an open-source property management platform. The flaw stems from a lack of token state management in the One-Time Password (OTP) authentication workflow. Adversaries can brute-force OTP values to authenticate as any registered user without additional credentials. The issue affects MicroRealEstate versions through 1.0.0-alpha3 and is classified under [CWE-288: Authentication Bypass Using an Alternate Path or Channel].

Critical Impact
Remote unauthenticated attackers can impersonate arbitrary MicroRealEstate users by brute-forcing OTP tokens, leading to full account takeover and exposure of tenant, landlord, and financial data.

Affected Products

MicroRealEstate versions through 1.0.0-alpha3
Deployments exposing the authentication API to untrusted networks
Self-hosted MicroRealEstate instances without upstream rate limiting

Discovery Timeline

2026-07-07 - CVE-2026-57867 published to NVD
2026-07-07 - Last updated in NVD database

Technical Details for CVE-2026-57867

Vulnerability Analysis

MicroRealEstate uses an OTP-based login flow. When a user requests access, the application generates a short numeric OTP and delivers it out-of-band. The server then accepts subsequent authentication attempts that present this OTP. The vulnerable implementation does not track token state across attempts. Each guess is validated independently against the expected value without invalidating the OTP after failed submissions or enforcing an attempt ceiling.

Because the OTP keyspace is small and the server places no state-bound limit on validation attempts, an attacker can iterate through all possible OTP values for a target account. The server responds with a valid session once the correct value is submitted. This turns a one-time secret into a brute-forceable credential.

Root Cause

The root cause is missing token state management in the authentication handler. The server does not decrement an attempt counter, mark OTPs as consumed after a failure threshold, or bind an OTP to a single verification transaction. As a result, the OTP behaves as a static short secret for the duration of its validity window.

Attack Vector

Exploitation requires only network access to the MicroRealEstate authentication endpoint. An unauthenticated attacker triggers OTP issuance for a target account, then submits automated requests iterating through the OTP keyspace until the server returns a valid session. No user interaction is required. Full technical detail is available in The Missing Link Security Advisory and the MicroRealEstate GitHub repository.

Detection Methods for CVE-2026-57867

Indicators of Compromise

High-volume POST requests to the MicroRealEstate OTP verification endpoint from a single source IP within the OTP validity window.
Successful authentication events preceded by dozens or hundreds of failed OTP submissions for the same account.
Session creations for accounts that did not originate an interactive OTP request from the legitimate user's device.

Detection Strategies

Alert when failed OTP validation attempts for one account exceed a low threshold (for example, 10) within the token lifetime.
Correlate OTP issuance events with the count and pacing of subsequent verification attempts per user.
Baseline typical login sequences and flag deviations such as rapid sequential numeric submissions.

Monitoring Recommendations

Ingest MicroRealEstate application and reverse proxy logs into a centralized logging or SIEM platform for correlation.
Monitor authentication endpoints for burst patterns and enumerate source IPs across accounts to detect distributed brute-force.
Track new session creations against MFA challenge counts to surface anomalous authentication ratios.

How to Mitigate CVE-2026-57867

Immediate Actions Required

Restrict network exposure of the MicroRealEstate authentication endpoint using a reverse proxy or firewall until a patched release is available.
Enforce rate limiting on OTP verification endpoints at the web tier, capping attempts per account and per source IP.
Rotate any sessions and credentials for accounts showing unexplained login activity during the exposure window.

Patch Information

No fixed release is listed for MicroRealEstate at the time of publication. The vulnerability affects releases through 1.0.0-alpha3. Operators should track upstream fixes via the MicroRealEstate GitHub repository and apply the vendor-supplied update once available.

Workarounds

Place MicroRealEstate behind a reverse proxy such as NGINX or Traefik and configure per-IP and per-account request throttling on the OTP verification path.
Increase OTP entropy by extending token length or reducing token lifetime through configuration where supported.
Restrict administrative and tenant portals to trusted networks or a VPN until the upstream fix is deployed.

bash

# NGINX rate limiting example for the OTP verification endpoint
http {
    limit_req_zone $binary_remote_addr zone=otp_ip:10m rate=5r/m;

    server {
        location /api/v2/authenticator/tenant/signedin {
            limit_req zone=otp_ip burst=3 nodelay;
            limit_req_status 429;
            proxy_pass http://microrealestate_backend;
        }
    }
}