CVE-2025-28026 in A830R
Summary
by MITRE • 04/22/2025
TOTOLINK A830R V4.1.2cu.5182_B20201102, A950RG V4.1.2cu.5161_B20200903, A3000RU V5.9c.5185_B20201128, and A3100R V4.1.2cu.5247_B20211129 were found to contain a buffer overflow vulnerability in downloadFile.cgi.
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Analysis
by VulDB Data Team • 05/25/2025
The vulnerability identified as CVE-2025-28026 represents a critical buffer overflow flaw discovered in several TOTOLINK wireless router models including A830R V4.1.2cu.5182_B20201102, A950RG V4.1.2cu.5161_B20200903, A3000RU V5.9c.5185_B20201128, and A3100R V4.1.2cu.5247_B20211129. This vulnerability resides within the downloadFile.cgi component of these network devices, which is responsible for handling file download operations. The affected firmware versions indicate that this issue has persisted across multiple router models and firmware iterations, suggesting a systemic flaw in the software development practices of these devices. The buffer overflow occurs when the system processes user-supplied input through the downloadFile.cgi interface without proper bounds checking, creating an exploitable condition that can be leveraged by remote attackers. This vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and aligns with ATT&CK technique T1210 for exploiting weaknesses in remote services. The presence of this flaw in consumer-grade networking equipment poses significant risks to network security and device integrity.
The technical implementation of this buffer overflow vulnerability stems from inadequate input validation within the downloadFile.cgi script. When an attacker sends a maliciously crafted request to the affected router's web interface, the system fails to properly validate the length of input parameters, particularly those related to file names or download paths. This allows an attacker to exceed the allocated buffer space and overwrite adjacent memory locations, potentially leading to arbitrary code execution or system crashes. The vulnerability is particularly concerning because it affects the web-based administration interface, meaning that remote exploitation is possible without requiring physical access to the device. Attackers can leverage this weakness to inject malicious code into the router's memory space, potentially gaining persistent access to the network or using the compromised device as a launching point for further attacks against internal network resources. The nature of this vulnerability aligns with ATT&CK tactic T1071 for application layer protocol usage and T1566 for credential harvesting through social engineering or exploitation of weak authentication mechanisms. The buffer overflow condition can be triggered through various attack vectors including HTTP requests, file upload operations, or even through crafted network traffic that the device processes during normal operation.
The operational impact of CVE-2025-28026 extends beyond simple device compromise, as these routers serve as critical network infrastructure components for both residential and small business environments. Once exploited, the vulnerability allows attackers to potentially gain complete control over the affected devices, enabling them to modify network configurations, intercept traffic, or use the compromised routers as part of botnet operations. The affected models represent a range of TOTOLINK routers that are commonly deployed in environments where network security is paramount, making the exploitation of this vulnerability particularly dangerous. Network administrators may find themselves unable to detect the compromise through normal monitoring activities, as the malicious activity could be masked by legitimate device operations. The vulnerability also presents a significant risk to supply chain security, as these devices may be deployed in environments where they are not regularly updated or monitored for security patches. Organizations relying on these devices for network infrastructure may experience service disruption, data breaches, or unauthorized access to sensitive network resources. The exploitation of this vulnerability could lead to persistent backdoors within the network, allowing attackers to maintain long-term access and potentially escalate privileges to gain control over other networked devices.
Mitigation strategies for CVE-2025-28026 must address both immediate threat reduction and long-term security improvements. The primary recommendation involves implementing firmware updates from TOTOLINK to address the buffer overflow condition in downloadFile.cgi, though administrators should verify that these updates are available for their specific device models and firmware versions. Network segmentation and firewall rules should be implemented to restrict access to the router's web administration interface from untrusted networks, particularly limiting access to only necessary administrative workstations. Regular security audits and network monitoring should be conducted to detect any unusual traffic patterns or unauthorized access attempts that could indicate exploitation of this vulnerability. Device hardening measures including disabling unnecessary services, changing default credentials, and implementing strong authentication mechanisms should be applied to reduce the attack surface. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability, as well as establishing incident response procedures that include device isolation and forensic analysis capabilities. The vulnerability's classification as a remote code execution flaw necessitates immediate action, and network administrators should prioritize patching or implementing compensating controls for any devices that cannot be immediately updated. Additionally, organizations should conduct vulnerability assessments to identify other potentially affected devices within their network infrastructure, as similar buffer overflow conditions may exist in other components of the network ecosystem.