Overview
In the ever-growing world of cybersecurity threats, a new vulnerability has emerged that is shaking the foundations of outdated network devices. The CVE-2025-5623 is a severe vulnerability identified in D-Link DIR-816 1.10CNB05, a product which is no longer supported by the manufacturer, making it a prime target for cybercriminals. This vulnerability exploits the ‘qosClassifier’ function of the file ‘/goform/qosClassifier. It is classified as critical due to its severe impact potential and the ease of its exploitation.
The primary concern regarding this vulnerability is that the attack can be initiated remotely, making any device with an internet connection a potential target. The disclosure of the exploit to the public further amplifies its threat level. It’s a race against time for network administrators and users to mitigate this vulnerability before falling victim to a potential system compromise or data leakage.
Vulnerability Summary
CVE ID: CVE-2025-5623
Severity: Critical (CVSS 9.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise and data leakage
Affected Products
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Product | Affected Versions
D-Link DIR-816 | 1.10CNB05
How the Exploit Works
The exploit takes advantage of a stack-based buffer overflow vulnerability within the ‘qosClassifier’ function of the file ‘/goform/qosClassifier. It involves the manipulation of the ‘dip_address’ or ‘sip_address’ argument, causing an excessive amount of data to be loaded into the stack memory, triggering a stack overflow. As a result, an attacker can execute arbitrary code or cause a denial of service, potentially leading to system compromise or data leakage.
Conceptual Example Code
Below is a conceptual example of how the vulnerability might be exploited. This is a simplified HTTP request that shows how an attacker might overload the ‘dip_address’ or ‘sip_address’ value with excessive data.
POST /goform/qosClassifier HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
dip_address=AAAAAAAA...[long string of As]...Note: The above is a conceptual representation and may not accurately reflect the actual code used in an attack.
Mitigation Guidance
While the ideal solution is to apply the vendor patch for this vulnerability, it is important to note that D-Link no longer supports the affected product. As a temporary mitigation, utilising Web Application Firewall (WAF) or Intrusion Detection System (IDS) can help to detect and prevent exploit attempts. However, considering the severity and potential impact of this vulnerability, users are strongly recommended to upgrade their network devices to models that are currently supported and regularly updated by the vendor.