CVE-2026-71934 in VigorSwitch G2540xs
Summary
by MITRE • 08/24/2026
Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the pingtrace function. The vulnerability is caused by missing length checks when the host, count, and interval fields are concatenated into a fixed-size buffer. A remote attacker can trigger this vulnerability via crafted input, causing a denial of service or potentially executing arbitrary commands. Exploitation requires valid administrative credentials for the device's web management interface.
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Analysis
by VulDB Data Team • 08/24/2026
The identified vulnerability resides within the pingtrace functionality of multiple DrayTek VigorSwitch models and represents a classic buffer overflow condition stemming from insufficient input validation. Specifically, the flaw occurs when the system concatenates user-supplied values for host address, packet count, and interval duration into a fixed-size memory buffer without performing adequate length checks. This architectural oversight allows an attacker to supply payload data that exceeds the allocated memory boundaries of the target buffer. In network infrastructure devices such as managed switches, functions like pingtrace are often exposed through administrative interfaces to facilitate diagnostic operations, making them high-value targets for exploitation if security controls are misconfigured or absent.
From a technical perspective, this vulnerability is categorized under CWE-120, which denotes Buffer Copy without Checking Size of Input. The absence of boundary checks means that when the concatenated string exceeds the buffer's capacity, it overwrites adjacent memory locations on the stack or heap. Depending on the specific compiler optimizations and operating system architecture employed by the device firmware, this memory corruption can lead to a crash of the affected process, resulting in a denial of service condition where the switch becomes unresponsive or requires a reboot. More critically, if an attacker carefully crafts the overflow payload to overwrite return addresses or function pointers within the control flow of the program, they may achieve arbitrary code execution on the device's underlying operating system.
The operational impact of this vulnerability is significant due to its potential for remote exploitation and privilege escalation. While the initial access vector requires valid administrative credentials for the web management interface, which limits the attack surface compared to unauthenticated exploits, it still poses a severe risk in environments where credential theft or insider threats are concerns. An attacker who gains control over an administrative account can leverage this flaw to compromise the integrity of the network infrastructure. Successful exploitation could allow the insertion of malicious firmware, interception of traffic passing through the switch, or use of the compromised device as a pivot point for further lateral movement within the internal network. This aligns with ATT&CK techniques related to Defense Evasion and Privilege Escalation, specifically those involving memory corruption exploits to bypass security restrictions.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary defense is to apply the vendor-provided firmware updates that patch this specific buffer overflow by implementing proper length validation before concatenating input fields into fixed buffers. Administrators should ensure that all connected devices are running the latest stable release of DrayTek VigorSwitch firmware. Additionally, access control measures should be strictly enforced; administrative interfaces must not be exposed to untrusted networks such as the public internet and should instead be restricted to trusted management VLANs or specific IP addresses using firewall rules. Multi-factor authentication for administrative accounts further reduces the risk of credential compromise leading to exploitation. Regular vulnerability scanning and penetration testing can help identify similar misconfigurations across the network infrastructure, ensuring that input validation is consistently applied across all diagnostic tools exposed by managed devices.