CVE-2026-0647 Overview
CVE-2026-0647 is an improper authentication vulnerability [CWE-306] in the embedded web server of the Rockwell Automation 1794-AENTR FLEX I/O EtherNet/IP adapter. An unauthenticated remote attacker can change the device's web interface password by sending a crafted HTTP GET request to a specific endpoint. The flaw requires no prior authentication, no user interaction, and is exploitable over the network.
Critical Impact
Successful exploitation enables full account takeover of the adapter's web interface, unauthorized configuration changes, and loss of availability for the embedded web server controlling industrial I/O communications.
Affected Products
- Rockwell Automation 1794-AENTR FLEX I/O EtherNet/IP Adapter
- Embedded web server component of the 1794-AENTR adapter
- Industrial control environments using the 1794-AENTR for FLEX I/O communications
Discovery Timeline
- 2026-06-16 - CVE-2026-0647 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2026-0647
Vulnerability Analysis
The 1794-AENTR adapter exposes an embedded web server that handles administrative functions including credential management. The password change endpoint fails to enforce authentication before processing requests. An attacker who can reach the device on the network can issue a single HTTP GET request to set a new password without supplying current credentials or a valid session.
The weakness is categorized under [CWE-306] Missing Authentication for Critical Function. The CVSS v4.0 metrics indicate network-reachable exploitation with low attack complexity, high impact on integrity and availability, and low impact on confidentiality of the adapter itself. EtherNet/IP adapters typically sit on flat operational technology (OT) networks, increasing exposure once an attacker reaches the control LAN.
Root Cause
The embedded web server's password modification handler does not validate session state or credentials before applying configuration changes. The administrative endpoint is reachable through unauthenticated HTTP GET requests, placing a security-critical operation outside any access control boundary.
Attack Vector
An attacker with network access to the adapter's web interface sends a crafted HTTP GET request to the vulnerable password-change endpoint. The server processes the request, overwrites the stored credential, and returns control of the web interface to the attacker. From there, the adapter can be reconfigured, denied to legitimate operators, or used as a foothold into the broader industrial network.
No verified public proof-of-concept code is available. Technical specifics are described in the Rockwell Automation Security Advisory SD1775.
Detection Methods for CVE-2026-0647
Indicators of Compromise
- Unexpected HTTP GET requests to the 1794-AENTR web interface password-change endpoint from non-administrative source addresses
- Unscheduled password changes on the adapter's embedded web server
- Operator lockout from the web interface or repeated failed logins by legitimate engineers
- Configuration drift on FLEX I/O adapters not matching change management records
Detection Strategies
- Inspect HTTP traffic to and from 1794-AENTR adapters for GET requests targeting credential-management URIs
- Correlate web interface authentication failures with prior unauthenticated GET requests to the same device
- Baseline normal engineering workstation IP ranges and alert on web access from unexpected hosts
Monitoring Recommendations
- Forward firewall and OT network sensor logs covering EtherNet/IP segments to a centralized analytics platform
- Enable HTTP request logging on perimeter devices fronting the control network
- Track adapter firmware versions and configuration hashes to identify unauthorized modifications
How to Mitigate CVE-2026-0647
Immediate Actions Required
- Restrict network reachability of 1794-AENTR adapters to authorized engineering workstations using ACLs or segmentation
- Apply firmware updates from Rockwell Automation as soon as they are made available in advisory SD1775
- Inventory all 1794-AENTR devices and verify current passwords have not been altered without authorization
- Disable the embedded web server on adapters where it is not required for operations
Patch Information
Refer to the Rockwell Automation Security Advisory SD1775 for the official fixed firmware versions and remediation guidance for the 1794-AENTR adapter.
Workarounds
- Place affected adapters behind an industrial firewall and permit HTTP access only from a hardened jump host
- Block inbound HTTP traffic to 1794-AENTR devices at the cell or zone boundary in accordance with ISA/IEC 62443 zoning
- Use VPN or zero trust network access for any remote engineering session that requires interacting with the adapter's web interface
- Monitor and alert on any HTTP traffic destined for adapter management interfaces from outside an approved allowlist
# Example: restrict HTTP access to the 1794-AENTR adapter using iptables on an upstream gateway
iptables -A FORWARD -p tcp -d <adapter_ip> --dport 80 -s <engineering_workstation_ip> -j ACCEPT
iptables -A FORWARD -p tcp -d <adapter_ip> --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
