CVE-2014-7277 Stored Server XSS in ZyXEL SBG-3300 Security Gateway

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#Vulnerability Title: Stored Server XSS in ZyXEL SBG-3300 Security Gateway
#Date: 02/10/2014
#CVE-ID: CVE-2014-7277
#Product: ZyXEL SBG3300-N series
#Vendor: www.zyxel.com
#Affected Firmware: Latest version at the time of disclosure V1.00(AADY.4)C0 and below (tested)
#Patch: Unpatched
#Authored by: Mirko Casadei
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#Disclosure Timeline:
13/08/2014  Vendor Contact with Acknowledgment
13/09/2014  No response from Vendor after first contact
02/10/2014  Full Disclosure

#Technical details:
The web interface of the Security Gateway is affected by a Stored Server XSS vulnerability in the main login page.
Abusing the login 'welcome message' form, an attacker can inject the XSS in HTML code.
Example of a working code:
..
<span class="title_index">Welcome</span><br>
<li id="loginMessage"><img src=x onerror=alert('XSS') /></li>
..

#Remediation
The vulnerable form should sanitize input.
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