Support Announcements
DSL-6740U Revsion H1 - Multiple Cross-Site Scripting (XSS) Vulnerabilities Present in Device Web-GUI Configuration



The D-Link DSL-6740U Wired/Wireless ADSL Gateway has vulnerabilities present that allows malicious attacks using Cross-Site Scripting (XSS) exploits. These vulnerabilities allows an attacker, who has an authorized (logged in) browser session to access to the Web-GUI configration, which allows the ability to change configuration or cause the product to be unreliable.


D-Link Security Incident Reponse Policy


All public communication on this issue will be offered at

Our security response team can be contacted for incident information or to report incidents at

Any non-critical security issue, help in updating firmware, or configuration regarding this issue please contact your D-Link Customer care channel.



CVE-2013-6811 - Liad Mizrachi

Secunia Advisory ID: 55999



General Disclosure


Security and performance is of the utmost importance to D-Link across all product lines. This is not just through the development process but also through regular firmware updates to comply with the current safety and quality standards. We are proactively working with the sources of these reports as well as continuing to review across the complete product line to ensure that the vulnerabilities discovered are addressed.  We will continue to update this page to include the relevant product firmware updates addressing these concerns. In the meantime, you can exercise the below cautions to avoid unwanted intrusion into your D-Link product.


Immediate Recommendations for all D-Link router customers


  • Do not enable the Remote Management feature since this will allow malicious users to use this exploit from the internet.  Remote Management is default disabled on all D-Link Routers and is included for customer care troubleshooting if useful and the customer enables it.
  • If you receive unsolicited e-mails that relates to security vulnerabilities and prompt you to action, please ignore it. When you click on links in such e-mails, it could allow unauthorised persons to access your router. Neither D-Link nor its partners and resellers will send you unsolicited messages where you are asked to click or install something.
  • Make sure that your wireless network is secure.
  • Do not provide your admin password to anyone. If required we suggest updating the password frequently.




The DSL-6740U router is susceptible to several Cross-site Scripting (XSS) attacks, which allow an attacker to forge submitted command that execute actions in an authorized (logged in) browser session. A malicious attacker can exploit this vulnerability on an unsuspecting device administrator, allowing changes to the administrator credentials and enablement remote management services.

Features that can be exploited are:

  • Advance —> Port Forwarding Setup —> Custom Service
  • Advance —>  Port Triggering —> Port Triggering Entries
  • Advance —>  Parental Control —> URL Filter
  • Advance —>  Print Server settings
  • Advance —>   QoS Queue Setup
  • Advance —>   QoS Classification Entries

Requirements for the vulneratiblity to be exploited are:

  • The victim must have an active logged in management session with the router.
  • The victim must be fooled in to performing an action (e.g., by clicking an attacker provided link), browse to a malicious or compromised site, or be the victim of a man-in-the-middle attack.

Due to the requirement of having to be authenticated (logged in) to the router, the threat of this attack has a narrow scope so the impact to users is also considered narrow.  We also are aware that a exploit to take advantage of the vulnerability is not impossible.  In a hardend system, an external user would not have access to excutable commands with-in the router, they should only be accessible by the router's itself, which is configured thru the Web_GUI only.


In order to comply and close this vulnerability D-Link will release new firmware that corrects this vulnerability.


Effected Products


Model Name

HW Version

Current FW Version

New FW Version for this exploit fix




FW. 1.01.19


Security patch for your D-Link router


These firmware updates address the security vulnerabilities in affected D-Link routers. D-Link will update this continually and we strongly recommend all users to install the relevant updates.


As there are different hardware revisions on our products, please check this on your device before downloading the correct corresponding firmware update. The hardware revision information can usually be found on the product label on the underside of the product next to the serial number. Alternatively, they can also be found on the device web configuration.


To update the firmware please log-in to the Web-GUI interface of your DSL-6740U, from the menu select Maintanence -> System -> Upgrade Firmware. If you require help please contact your regional D-Link customer care website for options.



DSL-6740U Revision All1
Firmware Patch: FW 1.01.19

Current status: December 12, 2013