CVE-2026-76133: Ebyte Product Authentication Bypass Vulnerability

CVE-2026-76133 Overview

CVE-2026-76133 affects an Ebyte industrial control system product that relies on a deprecated hashing algorithm during an authentication-related operation. The weak cryptographic construction reduces the assurance provided by the authentication mechanism. Attackers who can manipulate or predict the authentication exchange may leverage this weakness to gain unauthorized access to the device.

The vulnerability is tracked under CWE-327: Use of a Broken or Risky Cryptographic Algorithm and is documented in CISA ICS Advisory ICSA-26-237-06. The issue is network-exploitable, requires no privileges, and requires no user interaction.

Critical Impact
A network-based attacker can bypass authentication on the affected Ebyte product, compromising the confidentiality, integrity, and availability of the device.

Affected Products

Ebyte industrial communications product identified in CISA ICS Advisory ICSA-26-237-06
Specific model and firmware versions listed in the vendor advisory
Deployments in operational technology (OT) and industrial control system (ICS) environments

Discovery Timeline

2026-08-31 - CVE-2026-76133 published to NVD
2026-09-01 - Last updated in NVD database

Technical Details for CVE-2026-76133

Vulnerability Analysis

The affected Ebyte product implements an authentication routine that depends on a deprecated hashing algorithm. Modern cryptanalysis has shown such algorithms to be susceptible to collisions, precomputation, and reversal within practical time bounds. When the algorithm is used to protect authentication material, the security assurance the protocol is intended to provide collapses.

An attacker positioned to observe, replay, or influence the authentication exchange can derive or forge authentication artifacts. The CISA ICS Advisory ICSA-26-237-06 categorizes the flaw under CWE-327, which specifically covers the misuse of broken or risky cryptographic primitives in security-sensitive operations.

Exploitation of the flaw does not require credentials or interaction with a legitimate user. Because the affected product operates in ICS environments, successful exploitation can grant an attacker administrative access to a networked field device.

Root Cause

The root cause is the selection and continued use of a cryptographic hash function that is no longer considered secure for authentication contexts. The deprecated algorithm fails to provide the collision resistance and preimage resistance required to protect authentication data. Vendor firmware does not enforce a modern replacement such as SHA-256 or an authenticated construction like HMAC over a strong hash.

Attack Vector

Exploitation is reachable over the network. An adversary with connectivity to the device's management interface can intercept or predict the authentication exchange and produce a valid authenticator without possessing the underlying secret. The GitHub CSAF Report provides the structured advisory data describing the affected surface.

No public exploit code is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Technical details of the exchange are not published; refer to the vendor advisory for protocol-level specifics.

Detection Methods for CVE-2026-76133

Indicators of Compromise

Unexpected successful authentication events on Ebyte device management interfaces originating from unfamiliar source addresses
Configuration changes on affected devices without a corresponding change-management ticket
Repeated authentication attempts followed by a single successful login within a short time window

Detection Strategies

Inspect network traffic to and from Ebyte devices for authentication exchanges using the deprecated hashing primitive identified in the CISA advisory
Baseline normal administrative access patterns for each device and alert on deviations in source, time-of-day, or command sequence
Correlate authentication logs across devices to identify credential reuse patterns consistent with hash-based forgery

Monitoring Recommendations

Forward device syslog and authentication events to a centralized SIEM for correlation with network telemetry
Monitor east-west traffic within OT network segments where Ebyte devices operate, not only north-south boundaries
Alert on protocol anomalies such as malformed or non-standard authentication headers targeting affected devices

How to Mitigate CVE-2026-76133

Immediate Actions Required

Identify all Ebyte devices in scope and compare firmware versions against those listed in CISA ICS Advisory ICSA-26-237-06
Restrict network access to device management interfaces to a dedicated administrative VLAN or jump host
Rotate any credentials that have been used with the affected devices once a patched firmware is available
Enable and centralize logging of all authentication attempts against affected devices

Patch Information

Refer to the vendor guidance referenced in the CISA advisory for firmware updates that replace the deprecated hashing algorithm. Apply patches following an approved OT change-management process and validate device functionality after upgrade.

Workarounds

Segment affected devices behind a firewall that denies all inbound traffic except from designated management workstations
Terminate management sessions through a VPN or bastion host that enforces strong, modern authentication before reaching the device
Disable remote management interfaces on devices that do not require them for daily operations
Apply strict access control lists (ACLs) on switches and routers adjacent to affected devices

bash

# Example ACL restricting Ebyte device management access to a single admin subnet
access-list 110 permit tcp 10.10.50.0 0.0.0.255 host <ebyte_device_ip> eq 80
access-list 110 permit tcp 10.10.50.0 0.0.0.255 host <ebyte_device_ip> eq 443
access-list 110 deny   ip any host <ebyte_device_ip> log