CVE-2026-77022 in CF-N1-S
Summary
by MITRE • 08/20/2026
A security flaw has been discovered in Comfast CF-N1-S 2.6.0.1. Affected by this issue is the function sub_44B438 of the file /cgi-bin/mbox-config?method=SET§ion=ptest_ssid of the component SSID Configuration. The manipulation of the argument ssid results in stack-based buffer overflow. The attack can be executed remotely. The exploit has been released to the public and may be used for attacks.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified in Comfast CF-N1-S firmware version 2.6.0.1 represents a critical remote code execution risk stemming from improper input validation within the device's web management interface. Specifically, the flaw resides in the sub_44B438 function associated with the /cgi-bin/mbox-config endpoint when invoked with the method SET and section ptest_ssid parameters. This component is responsible for configuring SSID settings on wireless access points, a feature commonly used by administrators to manage network visibility and security policies. The core technical defect is a stack-based buffer overflow caused by the manipulation of the ssid argument passed during this configuration process. When an attacker supplies a specially crafted string that exceeds the expected buffer size allocated in memory for storing SSID data, the excess data overwrites adjacent memory locations on the call stack. This overwrite can corrupt return addresses or function pointers, allowing an attacker to redirect program execution flow arbitrarily.
From a technical perspective, this vulnerability aligns with CWE-121, which defines stack-based buffer overflow as a condition where software writes more data to a buffer than it is allocated to hold on the call stack. The absence of rigorous bounds checking or length validation before copying user-supplied input into fixed-size buffers creates this exploitable condition. Because the affected component is accessible via HTTP requests through the web interface, and assuming default configurations often leave such interfaces exposed without strong authentication or network segmentation, the attack vector is classified as remote. This means that an adversary does not need physical access to the device nor prior valid credentials if administrative access is weak or unpatched, significantly lowering the barrier for exploitation. The operational impact of successfully exploiting this vulnerability extends beyond simple denial of service; it typically results in arbitrary code execution with the privileges of the compromised process, which often runs as root on embedded Linux devices like routers and access points.
The availability of a public exploit further amplifies the severity of this issue by enabling automated attacks from threat actors who may not possess deep reverse engineering skills. Such exploits allow for rapid propagation across vulnerable networks, potentially leading to device compromise, installation of malware such as botnet clients or cryptominers, and use of the compromised hardware as a pivot point for lateral movement within internal network segments. This scenario is consistent with ATT&CK technique T1059, Command and Scripting Interpreter, where attackers execute commands on affected systems after gaining initial access through vulnerabilities like this buffer overflow. The compromise can also facilitate data exfiltration if sensitive configuration files or connected device credentials are accessible from the compromised context.
Mitigation strategies must prioritize immediate patching to the latest firmware version provided by Comfast, which should include fixes for input validation in the mbox-config handler. In cases where updating is not immediately feasible, network-level controls such as firewall rules restricting access to the management interface on port 80 or 443 to trusted IP addresses only can reduce exposure. Additionally, disabling remote administration features if they are not required and enforcing strong, unique administrative passwords can mitigate the risk of unauthorized exploitation. Security monitoring should also be enhanced to detect anomalous HTTP requests targeting the /cgi-bin/mbox-config endpoint with unusually long ssid parameters, which may indicate active probing or exploitation attempts for this specific buffer overflow vulnerability.