CVE-2026-1949: Delta Electronics AS320T Buffer Overflow

CVE-2026-1949 Overview

Delta Electronics AS320T contains a critical vulnerability involving incorrect calculation of the buffer size on the stack in the GET/PUT request handler of the web service. This improper buffer size calculation (CWE-131) can lead to memory corruption when processing specially crafted HTTP requests, potentially allowing remote attackers to execute arbitrary code or cause denial of service conditions on affected devices.

Critical Impact

This vulnerability allows unauthenticated remote attackers to exploit the web service's request handler through network-accessible endpoints, potentially leading to complete system compromise including arbitrary code execution with elevated privileges.

Affected Products

• Delta Electronics AS320T (all versions prior to security patch)
• Delta Electronics AS320T Web Service Component
• Industrial automation systems utilizing the vulnerable AS320T firmware

Discovery Timeline

• 2026-04-24 - CVE CVE-2026-1949 published to NVD
• 2026-04-24 - Last updated in NVD database

Technical Details for CVE-2026-1949

Vulnerability Analysis

The vulnerability exists in the web service component of the Delta Electronics AS320T device, specifically within the GET/PUT request handler functionality. The core issue stems from an incorrect calculation of the buffer size allocated on the stack when processing incoming HTTP requests.

When the web service receives GET or PUT requests, it allocates a stack-based buffer to store request data. Due to faulty size calculations, the allocated buffer may be smaller than the actual data being written to it. This creates a classic stack buffer overflow condition where an attacker can overflow the undersized buffer with malicious input, potentially overwriting adjacent stack memory including return addresses and saved registers.

The vulnerability is particularly severe because it requires no authentication and can be exploited remotely over the network. Successful exploitation could allow an attacker to gain complete control over the affected industrial device, disrupt operations, or use it as a pivot point for further network intrusion.

Root Cause

The root cause is CWE-131: Incorrect Calculation of Buffer Size. The web service fails to properly calculate the required buffer size before allocating memory on the stack. This miscalculation results in an insufficient buffer allocation that cannot safely accommodate the incoming request data, leading to a stack-based buffer overflow condition when oversized input is processed.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker can craft malicious GET or PUT HTTP requests with specially constructed payloads designed to overflow the undersized stack buffer. By carefully controlling the overflow data, an attacker can overwrite the return address on the stack to redirect program execution to attacker-controlled code, achieving remote code execution on the target device.

The vulnerability manifests in the GET/PUT request handler of the web service where buffer size calculations are performed incorrectly before stack allocation. Technical details and exploitation mechanics are available in the Delta Security Advisory.

Detection Methods for CVE-2026-1949

Indicators of Compromise

• Unusual or malformed HTTP GET/PUT requests to the AS320T web service with abnormally large payloads
• Unexpected crashes or restarts of the AS320T web service component
• Memory corruption indicators or segmentation faults in device logs
• Anomalous network traffic patterns targeting the device's web interface

Detection Strategies

• Deploy network intrusion detection systems (IDS) with signatures for oversized HTTP request payloads targeting industrial control devices
• Monitor HTTP traffic to AS320T devices for requests with suspicious payload sizes that exceed normal operational parameters
• Implement application-level logging to capture request sizes and identify buffer overflow attempts
• Use behavioral analysis to detect unusual patterns of GET/PUT requests to the web service

Monitoring Recommendations

• Continuously monitor network traffic to and from Delta Electronics AS320T devices for anomalous activity
• Implement alerting for HTTP requests that exceed expected payload thresholds
• Review device logs regularly for signs of service instability or unexpected restarts
• Establish baseline network behavior for industrial devices to identify deviations that may indicate exploitation attempts

How to Mitigate CVE-2026-1949

Immediate Actions Required

• Restrict network access to the AS320T web service to trusted IP addresses and networks only
• Implement network segmentation to isolate affected industrial devices from untrusted network segments
• Deploy web application firewall (WAF) rules to filter oversized or malformed HTTP requests
• Review and audit access controls for all Delta Electronics AS320T devices in your environment

Patch Information

Delta Electronics has released a security advisory addressing this vulnerability along with related issues (CVE-2026-1950, CVE-2026-1951, CVE-2026-1952). Organizations should consult the Delta Security Advisory PCSA-2026-00006 for detailed patch information and firmware update instructions. Apply the latest security updates from Delta Electronics as soon as they become available.

Workarounds

• Disable the web service on the AS320T device if it is not required for operational purposes
• Implement strict firewall rules to limit access to the web service port from only authorized management workstations
• Use a VPN or other secure tunnel for remote management access instead of direct network exposure
• Consider deploying an application-layer proxy that can inspect and sanitize HTTP traffic before it reaches the device

# Example firewall configuration to restrict access to AS320T web service
# Restrict web service access to trusted management network only
iptables -A INPUT -p tcp --dport 80 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP