CVE-2026-86530 in WSR-300HP
Summary
by MITRE • 09/28/2026
BUFFALO Wi-Fi products handle some web form input improperly to assemble command line strings internally. An administrative user may send a crafted HTTP request and execute an arbitrary OS command.
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Analysis
by VulDB Data Team • 09/28/2026
The vulnerability identified in BUFFALO Wi-Fi products represents a critical security flaw rooted in improper handling of web form inputs during the assembly of internal command-line strings. This issue is fundamentally classified as Command Injection, corresponding to CWE-78 in the Common Weakness Enumeration standard. The core technical failure lies in the application's lack of rigorous input validation and sanitization when processing data submitted through administrative web interfaces. When an administrator interacts with specific forms on the device's management console, the backend software directly incorporates user-supplied values into operating system commands without adequately escaping special characters or restricting allowed character sets. This architectural oversight allows malicious actors to inject additional shell commands that are executed by the underlying operating system with the privileges of the application process.
From an operational perspective, this vulnerability enables a remote attacker who possesses valid administrative credentials to achieve arbitrary code execution on the affected device. The attack vector is categorized under Remote Code Execution (RCE) and specifically aligns with MITRE ATT&CK technique T1059, which covers Command and Scripting Interpreter abuse. Because the flaw requires an authenticated user, it poses a significant risk in environments where administrative credentials may be weak, reused from other systems, or compromised through phishing or credential stuffing attacks. Once executed, the injected commands allow the attacker to interact with the device's file system, modify configuration files, install persistent backdoors, or pivot into the internal network segment connected to the router. This effectively compromises the confidentiality, integrity, and availability of both the endpoint device and any resources accessible through it.
The impact extends beyond simple command execution. In many embedded IoT devices like Wi-Fi routers, the application often runs with elevated privileges, such as root access, to manage hardware components and network interfaces. Consequently, successful exploitation grants the attacker full control over the operating system of the router. This can lead to severe consequences including DNS hijacking for traffic interception, man-in-the-middle attacks against connected clients, or using the compromised device as a launchpad for further lateral movement within the corporate or home network. Furthermore, attackers may exfiltrate sensitive data stored on the device, such as Wi-Fi passwords and configuration backups, leading to long-term security degradation even after the immediate vulnerability is addressed if persistence mechanisms are established.
Mitigation strategies must focus on both technical remediation and operational hardening. The primary defense involves applying vendor-provided firmware updates that patch this input validation flaw by implementing strict allow-listing of acceptable characters for form fields and properly escaping all user inputs before they are passed to system commands. In cases where immediate patching is not feasible, network segmentation should be employed to isolate the management interface from untrusted networks, ensuring it is only accessible via secure, authenticated channels such as HTTPS with strong certificate validation. Additionally, enforcing complex administrative passwords and disabling remote administration features when not strictly necessary reduces the attack surface significantly. Regular auditing of device configurations and monitoring for unusual outbound connections can also aid in early detection of exploitation attempts related to this CWE-78 vulnerability.