Symantec ASG and ProxySG Management Console Cross-Site Scripting Vulnerability [CVE-2016-10257]

A vulnerability in Symantec ProxySG Management Console could allow an unauthenticated, remote attacker to conduct cross-site scripting (XSS) attacks on a targeted system.

The vulnerability is due to insufficient sanitization of user-supplied input by the affected software. An attacker could exploit this vulnerability by persuading a user to visit a malicious URL. When the user visits the URL, the attacker could execute arbitrary script code in the user’s browser session in the security context of the affected site. An exploit could allow the attacker to view sensitive information, including the targeted user’s cookies and previously submitted web form data. This could allow the attacker to take further actions as the targeted user.

Symantec has confirmed the vulnerability and released software updates.


To exploit the vulnerability, the attacker may provide a link that directs a user to a malicious site and use misleading language or instructions to persuade the user to follow the provided link.


Administrators are advised to apply the appropriate updates.

Administrators are advised to allow only trusted users to have network access.

Users should verify that unsolicited links are safe to follow.

For additional information about cross-site scripting attacks and the methods used to exploit these vulnerabilities, see the Cisco Applied Mitigation Bulletin Understanding Cross-Site Scripting (XSS) Threat Vectors.

Administrators are advised to monitor affected systems.

Vendor Announcements

CVE Number – CVE-2016-10257

Symantec has released a security advisory at the following link: SA155

Fixed Software

Symantec has released a software patch to address this vulnerability. Customers are advised to follow Symantec’s instructions for applying the patch, which are available at the following links: Symantec ProxySG 6.5 and ProxySG

Duncan Newell

Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.

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