CVE-2026-73809: Ebyte Gateway Information Disclosure Flaw

CVE-2026-73809 Overview

CVE-2026-73809 is a cleartext transmission of sensitive information vulnerability [CWE-319] affecting certain Ebyte gateway products. The web management interface fails to adequately protect sensitive communications with transport-layer encryption. Attackers with access to network traffic can intercept authentication or session-related data exchanged between users and affected devices. Successful exploitation results in disclosure of sensitive information and unauthorized access to device management functionality.

The vulnerability is documented in CISA ICS Advisory ICSA-26-237-06, indicating impact on operational technology (OT) and industrial control environments where Ebyte gateways are deployed.

Critical Impact
A network-adjacent attacker can passively capture administrative credentials and session tokens transmitted in cleartext, leading to full compromise of the gateway management interface.

Affected Products

Ebyte gateway products (specific models identified in CISA ICS Advisory ICSA-26-237-06)
Web management interfaces on affected Ebyte gateways
Deployments exposing gateway management traffic on untrusted or shared networks

Discovery Timeline

2026-08-28 - CVE-2026-73809 published to NVD
2026-08-31 - Last updated in NVD database

Technical Details for CVE-2026-73809

Vulnerability Analysis

The flaw exists in the web management interface of affected Ebyte gateways. The interface transmits authentication credentials, session identifiers, and configuration data without transport-layer encryption such as Transport Layer Security (TLS). Any device on the same broadcast domain, upstream router, or intermediate network segment can observe this traffic.

Because industrial gateways typically bridge operational networks and IP infrastructure, an attacker with a foothold on the management network can enumerate administrator sessions passively. Once credentials are captured, the attacker authenticates directly to the gateway and gains full management control, including firmware, routing, and protocol-translation settings.

The Exploit Prediction Scoring System (EPSS) currently rates the probability of near-term exploitation at 0.167%, though EPSS does not account for internal OT network exposure where this class of flaw is most impactful.

Root Cause

The root cause is the absence, or improper enforcement, of transport-layer encryption on the device's HTTP-based management interface. Sensitive fields such as login POST bodies, session cookies, and Basic authentication headers travel as plaintext. This maps directly to CWE-319: Cleartext Transmission of Sensitive Information.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker performs passive traffic capture using standard tools such as tcpdump or Wireshark on a switch span port, a compromised host, or via ARP spoofing on a local segment. Captured credentials are then replayed against the gateway's management endpoint to obtain administrative access. Active machine-in-the-middle techniques can also inject or modify management requests since integrity is not protected.

No verified proof-of-concept code has been published. Details of exploitation would follow standard network sniffing methodology and are described in the CISA advisory.

Detection Methods for CVE-2026-73809

Indicators of Compromise

Unexpected administrative logins to Ebyte gateway management interfaces from unfamiliar source IP addresses
Configuration changes on the gateway (firmware, routing rules, user accounts) outside approved change windows
Presence of ARP spoofing artifacts or promiscuous-mode interfaces on hosts adjacent to gateway management VLANs

Detection Strategies

Inspect network flows to identify HTTP (TCP/80) traffic to Ebyte gateway management interfaces and flag any occurrence as suspect
Correlate successful gateway logins with prior packet-capture activity or unauthorized SPAN/mirror port configuration on adjacent switches
Enable authentication logging on the gateway where supported, and forward logs to a centralized SIEM for anomaly analysis

Monitoring Recommendations

Continuously monitor OT network segments for cleartext credential exposure using passive protocol analyzers
Alert on new or unauthorized MAC-to-IP bindings on management VLANs that may indicate ARP spoofing
Track administrative session sources against a known-good allowlist of jump hosts and management workstations

How to Mitigate CVE-2026-73809

Immediate Actions Required

Restrict access to the Ebyte gateway web management interface to a dedicated, isolated management VLAN
Require administrators to reach the gateway only through a hardened jump host or bastion with encrypted tunneling
Rotate all gateway administrator credentials that may have traversed untrusted network segments
Review the CISA ICS Advisory ICSA-26-237-06 for vendor-specific guidance and updated firmware availability

Patch Information

At the time of publication, refer to the CISA CSAF data file and the CISA ICS Advisory for the authoritative list of affected models and any vendor-provided firmware updates. Apply firmware that enables HTTPS on the management interface as soon as it becomes available from Ebyte.

Workarounds

Place gateways behind a VPN or IPsec tunnel so that management traffic is encrypted end-to-end even if the device only offers HTTP
Disable the web management interface when not in use and manage the gateway through a serial console or out-of-band channel
Implement network segmentation and strict access control lists (ACLs) to limit which hosts can reach the management port
Deploy static ARP entries or dynamic ARP inspection on management switches to reduce machine-in-the-middle risk

bash

# Example: restrict management access to a single jump host using an upstream ACL
# (adapt syntax to your switch/firewall platform)
access-list 110 permit tcp host 10.10.20.5 host 10.10.99.1 eq 80
access-list 110 deny   tcp any host 10.10.99.1 eq 80
access-list 110 permit ip any any
interface Vlan99
 ip access-group 110 in