A vulnerability was detected in D-Link DIR-816L 2_06_b09_beta. Affected by this vulnerability is the function authenticationcgi_main of the file /auth...
Description
A vulnerability was detected in D-Link DIR-816L 2_06_b09_beta. Affected by this vulnerability is the function authenticationcgi_main of the file /authentication.cgi. Performing manipulation of the argument Password results in stack-based buffer overflow. Remote exploitation of the attack is possible. The exploit is now public and may be used. This vulnerability only affects products that are no longer supported by the maintainer.
AI Analyst Comment
Remediation
Update A vulnerability was detected in Multiple Products to the latest version. Monitor for exploitation attempts and review access logs.
Executive Summary:
A critical vulnerability has been identified in certain D-Link router models, allowing a remote, unauthenticated attacker to gain complete control of the device. This flaw is due to a stack-based buffer overflow and is easily exploitable, with a public exploit already available. As the affected products are no longer supported by the vendor, they cannot be patched, posing a significant and permanent risk to network security.
Vulnerability Details
CVE-ID: CVE-2025-13188
Affected Software: D-Link DIR-816L
Affected Versions: DIR-816L firmware version 2_06_b09_beta. Other versions may also be affected; see vendor advisory for specific details.
Vulnerability: A remote, unauthenticated stack-based buffer overflow vulnerability exists in the
authenticationcgi_mainfunction of the device's web server. An attacker can send a specially crafted POST request to the/authentication.cgiendpoint with an excessively long string in thePasswordparameter. This overflows the buffer on the stack, allowing the attacker to overwrite critical program data and execute arbitrary code on the device, likely with root privileges.Business Impact
This vulnerability is rated as critical severity with a CVSS score of 9.8. Successful exploitation allows an attacker to gain full administrative control over the affected router. This can lead to severe consequences, including interception of all network traffic (man-in-the-middle attacks), unauthorized access to the internal network, deployment of malware, and using the compromised device as part of a botnet for launching further attacks like Distributed Denial-of-Service (DDoS). For a business, this translates to data breaches, network downtime, and a compromised network perimeter.
Remediation Plan
Immediate Action: The vendor no longer supports the affected product, meaning no security patches will be released. The primary and most effective remediation is to immediately decommission and replace the affected D-Link DIR-816L devices with a supported model. Until replacement is complete, restrict all external access to the device's management interface.
Proactive Monitoring: Monitor network traffic for anomalous POST requests to the
/authentication.cgifile, specifically looking for requests with abnormally long values for thePasswordparameter. Review firewall and web server logs for connection attempts to this endpoint from untrusted external sources. Monitor the device for unusual outbound traffic, which could indicate a successful compromise.Compensating Controls: If immediate replacement is not possible, implement the following controls as a temporary measure:
Exploitation Status
Public Exploit Available: true
Analyst Notes: As of the publication date of Nov 14, 2025, a functional public exploit is available for this vulnerability. The End-of-Life (EOL) status of the hardware means that it will remain permanently vulnerable, making it an attractive target for attackers scanning for low-effort targets.
Analyst Recommendation
Given the critical severity (CVSS 9.8), the availability of a public exploit, and the End-of-Life status of the product, this vulnerability represents an unacceptable risk. We strongly recommend that all identified D-Link DIR-816L routers be immediately removed from the network and replaced with currently supported hardware. Compensating controls should be considered a temporary bridge to replacement and not a long-term solution. While not currently on the CISA KEV list, its characteristics make it a prime candidate for inclusion, and organizations should treat it with the highest priority.