PT-2011-39: Denial of Service in Citrix XenServer Workload Balancer

(PT-2011-39) Positive Technologies Security Advisory 
Denial of Service in Citrix XenServer Workload Balancer

Vulnerable software

Citrix XenServer Workload Balancer 
Version: and earlier

Application link:

Severity level

Severity level: High 
Impact: Denial of Service 
Access Vector: Network exploitable 

CVSS v2: 
Base Score: 7.8 
Vector: (AV:N/AC:L/Au:N/C:N/I:N/A:C)

CVE: not assigned


Vulnerability description

Positive Research Center has discovered a Denial of Service vulnerability in Citrix XenServer Workload Balancer.

Remote attackers can cause an unhandled exception in the DwmWebSvc component by sending a specially crafted HTTP request.

How to fix

Update your software up to the latest version

Advisory status

10.11.2011 - Vendor is notified
10.11.2011 - Vendor gets vulnerability details
13.03.2012 - Vendor releases fixed version and details
27.03.2012 - Public disclosure


The vulnerability was discovered by Kirill Mosolov, Positive Research Center (Positive Technologies Company)


Reports on the vulnerabilities previously discovered by Positive Research:

About Positive Technologies

Positive Technologies is among the key players in the IT security market in Russia.

The principal activities of the company include the development of integrated tools for information security monitoring (MaxPatrol); providing IT security consulting services and technical support; development of the Securitylab leading Russian information security portal.

Among the clients of Positive Technologies, there are more than 40 state enterprises, more than 50 banks and financial organizations, 20 telecommunication companies, more than 40 plant facilities, as well as IT, service and retail companies from Russia, the CIS countries, the Baltic States, China, Ecuador, Germany, Great Britain, Holland, Iran, Israel, Japan, Mexico, the Republic of South Africa, Thailand, Turkey, and the USA.

Positive Technologies is a team of highly skilled developers, advisers and experts with years of vast hands-on experience. The company specialists possess professional titles and certificates; they are the members of various international societies and are actively involved in the IT security field development.