CVE-2023-40797 in AC23
Summary
by MITRE • 08/25/2023
In Tenda AC23 v16.03.07.45_cn, the sub_4781A4 function does not validate the parameters entered by the user, resulting in a post-authentication stack overflow vulnerability.
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Analysis
by VulDB Data Team • 01/29/2026
The vulnerability identified as CVE-2023-40797 resides within the Tenda AC23 router firmware version 16.03.07.45_cn where the sub_4781A4 function fails to properly validate user-supplied parameters. This critical flaw represents a stack-based buffer overflow condition that occurs during post-authentication operations, meaning an attacker must first establish valid credentials to exploit this vulnerability. The absence of input validation in this specific function creates a pathway for malicious actors to manipulate stack memory through crafted inputs that exceed the allocated buffer space. This particular implementation flaw demonstrates a fundamental failure in secure coding practices where the developers did not implement proper bounds checking or parameter validation mechanisms. The vulnerability falls under the CWE-121 category of stack-based buffer overflow, which is classified as a critical security weakness in software development. According to the ATT&CK framework, this vulnerability maps to T1210 - Exploitation for Privilege Escalation, as it requires authentication but can potentially lead to unauthorized system access. The affected router model represents a common consumer-grade networking device that serves as a critical entry point for home and small office networks, making it an attractive target for attackers seeking persistent access to network infrastructure.
The technical exploitation of this vulnerability occurs when an authenticated user submits malicious input to parameters handled by the sub_4781A4 function. The function's lack of parameter validation means that arbitrary data can be written beyond the allocated stack buffer boundaries, potentially overwriting adjacent memory locations including return addresses, function pointers, and other critical control data. This overflow condition creates opportunities for attackers to execute arbitrary code with the privileges of the affected process, typically corresponding to the router's web administration interface. The post-authentication requirement indicates that the vulnerability cannot be exploited remotely without prior credentials, but this limitation does not mitigate the severity of the potential impact. Attackers could leverage this vulnerability to gain full administrative control over the router, potentially enabling them to modify network configurations, redirect traffic, or establish persistent backdoors. The stack overflow occurs in a context where the application is already running with elevated privileges, making the exploitation particularly dangerous for network security.
The operational impact of CVE-2023-40797 extends beyond simple privilege escalation to encompass broader network compromise scenarios. Once successfully exploited, attackers could manipulate the router's core functionality to redirect DNS queries, intercept network traffic, or disable security features. The vulnerability affects the Tenda AC23 device family, which represents a significant portion of consumer-grade wireless routers deployed in residential and small business environments. These devices often serve as the primary gateway for network traffic and may be configured with default credentials that are easily discoverable, increasing the likelihood of successful exploitation. The vulnerability's presence in firmware versions indicates that the issue has persisted across multiple releases, suggesting a systemic problem in the development and testing processes rather than an isolated incident. Organizations and individuals using affected routers face potential exposure to man-in-the-middle attacks, network disruption, and unauthorized access to connected devices. The impact is particularly concerning given that many users do not regularly update their router firmware, leaving these vulnerable devices exposed for extended periods.
Mitigation strategies for CVE-2023-40797 require immediate attention from affected users and network administrators. The primary recommendation involves updating the router firmware to the latest version provided by Tenda, which should contain patches addressing the stack overflow vulnerability. Organizations should conduct comprehensive inventory assessments to identify all affected devices within their network infrastructure and prioritize remediation efforts accordingly. Network segmentation and access control measures can provide additional defense-in-depth layers, limiting the potential impact if a device becomes compromised. Regular firmware update policies should be implemented across all network infrastructure devices to prevent similar vulnerabilities from persisting. Security monitoring systems should be configured to detect anomalous network behavior that might indicate exploitation attempts, including unusual traffic patterns or unauthorized configuration changes. The vulnerability highlights the importance of secure coding practices and proper input validation in embedded systems, particularly those handling network communications. Organizations should consider implementing automated vulnerability scanning tools to identify similar issues in other network devices and ensure that firmware updates are applied promptly when available. The incident underscores the necessity of maintaining current security awareness and the critical role that timely patch management plays in protecting network infrastructure from exploitation.