CVE-2026-79666: Ech0 Authorization Bypass Vulnerability

CVE-2026-79666 Overview

CVE-2026-79666 is a missing authorization vulnerability [CWE-862] in Ech0 versions before 4.4.3. The application fails to enforce administrator-level authorization on dashboard log endpoints. Any authenticated user can query GET /api/system/logs and subscribe to Server-Sent Events (SSE) and WebSocket log streams. This exposes sensitive operational data including file paths, stack traces, and internal URLs to low-privileged accounts.

Critical Impact
Authenticated low-privileged users can retrieve system logs intended for administrators, leaking internal infrastructure details useful for follow-on attacks.

Affected Products

Ech0 versions before 4.4.3
Dashboard log HTTP endpoint (GET /api/system/logs)
Real-time log streaming endpoints (SSE and WebSocket)

Discovery Timeline

2026-08-25 - CVE-2026-79666 published to NVD
2026-08-27 - Last updated in NVD database

Technical Details for CVE-2026-79666

Vulnerability Analysis

Ech0 exposes a set of dashboard log endpoints intended for administrator use. The endpoints include a REST endpoint returning historical log data and two streaming interfaces built on SSE and WebSocket protocols. The server verifies that the requester holds a valid session but does not check whether the associated user has administrator privileges.

Any authenticated user, including newly registered or low-privileged accounts, can therefore read live and historical application logs. The exposed data commonly includes absolute filesystem paths, framework stack traces, internal service URLs, request identifiers, and error contexts. Attackers can use this information to map the application's internal structure, identify installed dependencies, and locate additional attack surface.

Root Cause

The root cause is a missing authorization check on the log-serving handlers. Authentication middleware confirms session validity, but the log routes lack a role or permission gate restricting access to administrators. This design gap places privileged telemetry behind an authenticated-only boundary rather than an administrator-only boundary.

Attack Vector

Exploitation requires network access to the Ech0 dashboard and a valid user session. An attacker registers or compromises a standard account, then issues an HTTP GET request to /api/system/logs to pull buffered log entries. The attacker can also open an SSE subscription or upgrade a connection to the WebSocket log stream to receive log events in real time. No additional user interaction or elevated privileges are required. See the GitHub Security Advisory and the VulnCheck Advisory on Ech0 for further technical detail.

Detection Methods for CVE-2026-79666

Indicators of Compromise

Requests to /api/system/logs from user accounts that are not members of the administrator role.
SSE or WebSocket subscriptions to log-stream endpoints originating from non-administrator sessions.
Repeated log-endpoint access patterns from a single low-privileged session, especially paired with authenticated reconnaissance requests.

Detection Strategies

Review Ech0 access logs for HTTP GET /api/system/logs requests and correlate the requesting user identifier against the administrator role membership list.
Alert on WebSocket upgrade or SSE Accept: text/event-stream requests targeting log endpoints from non-administrator principals.
Baseline normal administrator IP ranges and flag log-endpoint access from unexpected client addresses or user agents.

Monitoring Recommendations

Forward Ech0 application logs and reverse-proxy logs to a centralized logging platform for role-aware query and retention.
Track authentication events and correlate new low-privileged account creation with subsequent access to administrative routes.
Monitor for outbound reuse of internal paths, hostnames, or URLs that appear in Ech0 logs, which can indicate that leaked telemetry is being weaponized.

How to Mitigate CVE-2026-79666

Immediate Actions Required

Upgrade Ech0 to version 4.4.3 or later, which enforces administrator authorization on the affected endpoints.
Audit account inventory and disable inactive or unexpected user accounts that could be leveraged to reach the log endpoints.
Rotate credentials, tokens, and internal URLs that may have been exposed in previously served log output.

Patch Information

The maintainer addressed the issue in Ech0 4.4.3 by adding administrator authorization checks on the dashboard log endpoints, including the REST route and the SSE and WebSocket streaming routes. Upgrade details and fix references are available in the GitHub Security Advisory GHSA-cp79-9mwr-wr49.

Workarounds

Restrict access to /api/system/logs and the SSE/WebSocket log routes at the reverse proxy, allowing only administrator source IP ranges until the upgrade is applied.
Disable self-service user registration to reduce the population of authenticated principals able to reach the endpoints.
Reduce log verbosity so that stack traces, absolute paths, and internal URLs are not written to endpoints reachable by non-administrators.

bash

# Example nginx restriction for the affected routes
location ~ ^/api/system/logs {
    allow 10.0.0.0/24;   # administrator subnet
    deny  all;
    proxy_pass http://ech0_backend;
}