CVE-2026-76179: Ebyte Gateway Auth Bypass Vulnerability

CVE-2026-76179 Overview

CVE-2026-76179 is an improper protection of authentication tokens vulnerability affecting certain Ebyte gateway products. The web management interface handles session tokens insecurely on the client side, exposing them to attackers who can access session information. An attacker who obtains a valid token can replay it to impersonate an authenticated user and reach device management functionality. The weakness is tracked under CWE-598, which covers use of GET requests with sensitive query strings and related client-side exposure patterns. Because Ebyte gateways are commonly deployed in industrial and operational technology (OT) environments, CISA published this issue as ICS Advisory ICSA-26-237-06.

Critical Impact
Remote, unauthenticated attackers who capture an exposed session token can impersonate administrators of Ebyte gateway devices and gain full access to device management functions.

Affected Products

Ebyte gateway products (specific models per CISA advisory ICSA-26-237-06)
Web management interface component of affected gateways
Deployments exposing the management interface to untrusted networks

Discovery Timeline

2026-08-28 - CVE-2026-76179 published to NVD
2026-08-31 - Last updated in NVD database

Technical Details for CVE-2026-76179

Vulnerability Analysis

The flaw resides in how the Ebyte gateway web management interface handles authentication tokens during client-side session management. Tokens are insufficiently protected, meaning they can be exposed through channels reachable by an attacker. Once a valid token is captured, the server accepts it as proof of an authenticated session and grants full management privileges. The vulnerability requires no prior authentication and no user interaction, and it is reachable over the network. This class of weakness [CWE-598] typically arises when tokens are transmitted through URLs, cached by intermediaries, written to browser history, stored in unprotected client-side locations, or logged by proxies and monitoring systems.

Root Cause

The root cause is insecure client-side session handling within the gateway's web management interface. The application does not adequately restrict where authentication tokens travel or how they are stored, allowing tokens to leak into observable locations. Because the tokens themselves are not bound to additional context such as client identity, source address, or a short-lived nonce, a captured token remains valid for reuse.

Attack Vector

An attacker positioned to observe session artifacts, whether through referer headers, proxy logs, browser caches, or exposed telemetry, can extract a valid token. The attacker then replays the token against the gateway's management interface to establish an authenticated session. Successful exploitation yields administrative access to device management functionality, which on an OT gateway can extend to configuration changes, credential harvesting, and manipulation of downstream serial or field devices. The EPSS score at publication is 0.434%.

No verified public exploit code is available. See the CISA ICS Advisory ICSA-26-237-06 and the corresponding CSAF JSON data for authoritative technical details.

Detection Methods for CVE-2026-76179

Indicators of Compromise

Unexpected authenticated sessions to the gateway web management interface from unfamiliar source addresses or user agents.
Configuration changes on the gateway that do not correlate with authorized administrator activity or change-management tickets.
Repeated requests to management endpoints using identical session tokens from multiple source IPs.
Presence of session tokens in web server access logs, proxy logs, or referer headers reaching external destinations.

Detection Strategies

Correlate authentication events on Ebyte gateways with source IP, geolocation, and time-of-day baselines to surface token replay.
Inspect network telemetry for management interface access from OT network segments that normally do not initiate such sessions.
Alert on the same authentication token appearing in requests from more than one source within a short window.

Monitoring Recommendations

Forward gateway web interface access logs to a centralized SIEM or data lake for retention and correlation.
Monitor egress traffic from OT segments for HTTP referer or query-string leakage carrying session identifiers.
Track administrative actions on gateways and require corroboration with authorized change records.

How to Mitigate CVE-2026-76179

Immediate Actions Required

Restrict network access to the gateway web management interface using firewall rules, ACLs, or VPN gating so it is unreachable from untrusted networks.
Rotate all administrative credentials and invalidate active sessions on affected gateways.
Review CISA advisory ICSA-26-237-06 and apply vendor guidance as soon as it is published.
Audit recent gateway activity for signs of unauthorized configuration changes.

Patch Information

At the time of publication, no fixed version is enumerated in the NVD entry for CVE-2026-76179. Refer to the CISA ICS Advisory ICSA-26-237-06 and Ebyte vendor communications for firmware updates. Apply updates through a controlled OT change-management process and validate device operation after upgrade.

Workarounds

Place affected gateways behind a jump host or management VLAN reachable only through multi-factor authenticated VPN.
Terminate TLS at a reverse proxy that strips referer headers and prevents session tokens from appearing in URLs or logs.
Disable remote administration where local or out-of-band management is feasible.
Segment OT networks per CISA guidance in Defense in Depth Strategies so gateway compromise cannot pivot into control networks.

bash

# Example: restrict gateway management interface to a trusted jump host (iptables)
iptables -A INPUT -p tcp --dport 443 -s 10.10.20.5 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
iptables -A INPUT -p tcp --dport 80  -j DROP