CVE-2024-39802 in AC3000
Summary
by MITRE • 01/14/2025
Multiple buffer overflow vulnerabilities exist in the qos.cgi qos_settings() functionality of Wavlink AC3000 M33A8.V5030.210505. A specially crafted HTTP request can lead to stack-based buffer overflow. An attacker can make an authenticated HTTP request to trigger these vulnerabilities.A buffer overflow vulnerability exists in the `qos_dat` POST parameter.
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Analysis
by VulDB Data Team • 08/22/2025
The vulnerability identified as CVE-2024-39802 represents a critical stack-based buffer overflow within the qos.cgi component of Wavlink AC3000 M33A8.V5030.210505 firmware, specifically within the qos_settings() function. This flaw resides in the handling of the `qos_dat` POST parameter, which processes Quality of Service configuration data through HTTP requests. The vulnerability manifests when the system fails to properly validate the length of input data submitted via the qos_dat parameter, allowing an attacker to exceed the allocated buffer space on the stack. The affected device operates under the assumption that incoming data will not exceed predetermined limits, creating an exploitable condition where malicious input can overwrite adjacent stack memory locations.
The technical implementation of this vulnerability stems from inadequate input validation and bounds checking mechanisms within the firmware's web interface handling code. When an authenticated user submits a crafted HTTP request containing an oversized `qos_dat` parameter, the system's insufficient buffer size validation allows the input to overflow into adjacent memory segments. This stack-based overflow can potentially overwrite return addresses, function pointers, and other critical stack data structures, providing an attacker with opportunities for arbitrary code execution or system instability. The vulnerability specifically aligns with CWE-121 Stack-based Buffer Overflow, which occurs when data is written beyond the bounds of a stack-allocated buffer, and represents a common vector for privilege escalation and remote code execution attacks.
The operational impact of this vulnerability extends beyond simple system instability to potentially enable full system compromise. An authenticated attacker with access to the device's web interface can leverage this flaw to execute arbitrary code on the affected router, potentially gaining root privileges and establishing persistent access to the network infrastructure. The implications are particularly severe for enterprise environments where these devices serve as critical network gateways, as they could provide attackers with a foothold for lateral movement and data exfiltration. The vulnerability's exploitation requires only authenticated access, making it more accessible than unauthenticated attacks but still represents a significant risk to network security. This scenario aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: PowerShell, where attackers can execute malicious code through compromised network devices.
Mitigation strategies for CVE-2024-39802 should focus on immediate firmware updates from Wavlink, as the vendor has likely released patches addressing this specific vulnerability. Network administrators should implement strict access controls and monitor for unauthorized access attempts to router web interfaces, particularly during the period when the device remains vulnerable. The implementation of web application firewalls and input validation rules can help detect and prevent malicious requests containing oversized parameters. Additionally, network segmentation and least privilege principles should be enforced to limit the potential impact if exploitation occurs. Regular security audits of network infrastructure components and maintaining up-to-date vulnerability assessments are essential practices to prevent similar issues from arising in other network devices. Organizations should also consider implementing network monitoring solutions that can detect anomalous traffic patterns consistent with buffer overflow exploitation attempts, particularly focusing on unusual POST request sizes and malformed parameter values that could indicate exploitation attempts against similar vulnerabilities.