CVE-2025-3116: Controller Denial of Service Vulnerability

CVE-2025-3116 Overview

CVE-2025-3116 is an improper input validation vulnerability [CWE-20] affecting a Schneider Electric controller product. An authenticated attacker can send a malformed HTTPS request containing improperly formatted body data to the controller, triggering a denial of service condition. The flaw is exploitable over the network and requires low privileges but no user interaction. Successful exploitation impacts availability of the targeted controller without affecting confidentiality or integrity. Schneider Electric documented the issue in security notice SEVD-2025-161-02.

Critical Impact
An authenticated remote attacker can crash or disrupt a Schneider Electric controller by sending a specially crafted HTTPS request with a malformed body, causing loss of availability for the industrial control device.

Affected Products

Schneider Electric controller product referenced in advisory SEVD-2025-161-02
Specific product models and firmware versions are enumerated in the vendor advisory
Refer to the Schneider Electric Security Notice for the authoritative product and version list

Discovery Timeline

2025-06-10 - CVE-2025-3116 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-3116

Vulnerability Analysis

The vulnerability is classified as improper input validation [CWE-20] within the HTTPS request-handling logic of the affected Schneider Electric controller. The controller does not correctly validate the structure and content of body data submitted in HTTPS requests. When malformed body content is processed, the request handler enters an unexpected state that leads to a denial of service condition on the device.

Because the affected asset is an industrial controller, a denial of service can interrupt process visibility, control loops, or engineering workstation communications. Operators may experience loss of view or loss of control until the device is restarted or the offending session is terminated.

Root Cause

The root cause is missing or insufficient validation of HTTPS request body data before it is parsed and consumed by the controller's web services. Malformed formatting in the body is not rejected early, allowing the request to reach code paths that cannot safely handle it. The vendor advisory SEVD-2025-161-02 provides the authoritative technical description of the affected component.

Attack Vector

Exploitation requires network reachability to the controller's HTTPS interface and valid authentication credentials. An authenticated attacker constructs an HTTPS request whose body deviates from the expected format and submits it to the controller. The controller processes the malformed payload and enters a denial of service state. No user interaction is required, and the attack complexity is low. The vulnerability does not permit code execution, information disclosure, or data tampering based on the vendor description.

Code-level exploitation details are not published. See the Schneider Electric Security Notice for vendor-supplied technical details.

Detection Methods for CVE-2025-3116

Indicators of Compromise

Unexpected controller reboots, watchdog resets, or loss of communication with engineering workstations following HTTPS traffic
HTTPS requests to the controller management interface with anomalous Content-Length, chunked encoding, or malformed body payloads
Authenticated sessions originating from non-engineering hosts or from outside expected OT network segments
Repeated connection failures or TLS resets from a single source targeting the controller web service

Detection Strategies

Enable HTTPS access logging on the controller and forward records to a central SIEM for correlation with device availability events
Deploy an OT-aware intrusion detection system that inspects industrial protocol and HTTPS traffic for malformed body content directed at controllers
Alert on authentication events for controller administrative interfaces that originate from unexpected user accounts or network zones
Correlate controller uptime metrics with preceding HTTPS traffic to identify request-triggered denial of service patterns

Monitoring Recommendations

Continuously monitor controller availability, CPU utilization, and communication status through the historian or SCADA platform
Baseline normal HTTPS request patterns to the controller and alert on deviations in request size, frequency, or source
Track failed and successful authentications to controller web services, with priority alerting on off-hours activity
Retain full packet capture on OT network segments hosting affected controllers to support post-incident analysis

How to Mitigate CVE-2025-3116

Immediate Actions Required

Apply the firmware update or remediation guidance published in Schneider Electric advisory SEVD-2025-161-02 to all affected controllers
Restrict network access to controller HTTPS interfaces so that only authorized engineering workstations and jump hosts can reach them
Rotate credentials on affected controllers and remove unused accounts to reduce the authenticated attack surface
Segment operational technology (OT) networks from information technology (IT) networks with firewalls that enforce allow-listed protocols

Patch Information

Schneider Electric has issued security notice SEVD-2025-161-02, which contains the affected product list, fixed firmware versions, and remediation instructions. Consult the Schneider Electric Security Notice for authoritative patch guidance and scheduling considerations specific to industrial deployments.

Workarounds

Disable the HTTPS management interface on the controller if it is not operationally required
Place affected controllers behind a firewall that restricts inbound HTTPS traffic to a defined set of source addresses
Enforce virtual private network (VPN) or jump-host access for any remote administration of controllers
Monitor controller health and configure automatic notification for unexpected reboots or communication loss until firmware updates are applied

bash

# Example firewall rule restricting controller HTTPS access to engineering workstation subnet
iptables -A FORWARD -p tcp -s 10.20.30.0/24 -d <controller_ip> --dport 443 -j ACCEPT
iptables -A FORWARD -p tcp -d <controller_ip> --dport 443 -j DROP