CVE-2025-0727 in ThreadX NetX Duo
Summary
by MITRE • 02/21/2025
In NetX HTTP server functionality of Eclipse ThreadX NetX Duo before version 6.4.2, an attacker can cause an integer underflow and a subsequent denial of service by writing a very large file, by specially crafted packets with Content-Length in one packet smaller than the data request size of the other packet. A possible workaround is to disable HTTP PUT support.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/31/2025
The vulnerability identified as CVE-2025-0727 affects the NetX HTTP server functionality within Eclipse ThreadX NetX Duo versions prior to 6.4.2. This issue represents a critical security flaw that stems from improper handling of HTTP request processing, specifically when dealing with file upload operations. The vulnerability manifests as an integer underflow condition that occurs during the processing of HTTP PUT requests, creating a potential pathway for denial of service attacks that can severely impact system availability and operational continuity.
The technical flaw exploits a condition where an attacker can manipulate HTTP Content-Length headers in a manner that causes integer underflow during file transfer operations. This occurs when the initial packet contains a Content-Length value that is smaller than the actual data request size in subsequent packets. The vulnerability is particularly dangerous because it allows an attacker to craft specially designed packets that can trigger the underflow condition without requiring authentication or privileged access. This type of vulnerability falls under the CWE-191 category of Integer Underflow, which is classified as a weakness that can lead to unpredictable behavior and potential system compromise. The flaw is particularly concerning in embedded systems and networked environments where ThreadX NetX Duo is deployed, as these systems often operate with limited resources and may not have robust error handling mechanisms.
The operational impact of this vulnerability extends beyond simple denial of service, as it can potentially lead to complete system instability and service disruption. When the integer underflow occurs, the HTTP server may crash or become unresponsive, preventing legitimate users from accessing services while the system remains in a degraded state. The vulnerability affects the core HTTP server functionality, which means that any application relying on NetX Duo for web services or file transfer capabilities could be compromised. This represents a significant risk for industrial control systems, IoT devices, and embedded network appliances where ThreadX NetX Duo is commonly deployed. The vulnerability can be exploited by attackers who do not require specialized knowledge of the underlying system architecture, making it particularly dangerous in environments where security controls are minimal or absent.
The recommended mitigation strategy involves disabling HTTP PUT support within the NetX Duo configuration as a temporary workaround until a proper patch can be applied. This approach aligns with security best practices for vulnerability remediation, particularly when dealing with zero-day exploits where immediate action is required. However, the more comprehensive solution requires upgrading to NetX Duo version 6.4.2 or later, which includes patches specifically designed to address the integer underflow condition. Organizations should also consider implementing network segmentation and access controls to limit exposure while applying the necessary updates. The vulnerability demonstrates the importance of proper input validation and robust error handling in network services, as highlighted by ATT&CK technique T1499.004 for Network Denial of Service, which emphasizes the need for resilient service architectures that can withstand malicious input manipulation. Additionally, this vulnerability underscores the critical importance of maintaining up-to-date embedded system software and implementing regular security assessments to identify and remediate similar weaknesses in industrial control systems and network infrastructure components.