A security flaw in the Citrix Presentation Server Session Reliability service has been found recently. The Session Reliability service is used by some Citrix products to improve user experience when connecting over unreliable networks. By sending a specifically crafted request to this service, an attacker could establish a TCP connection to any port on the local machine. This could be used by the attacker to bypass network security policies and remotely access local ports on the target machine.

This vulnerability is present in the following versions of Citrix products:

  • Citrix MetaFrame Presentation Server 3.0
  • Citrix MetaFrame Presentation Server 4.0
  • Citrix Access Essentials 1.0
  • Citrix Access Essentials 1.5

No other versions of Citrix Presentation Server, Citrix Access Essentials or Citrix Desktop Server are affected by this issue.

Customers running an affected product with the Session Reliability feature disabled are not affected by this issue.

Downloads for all languages are available here (CTX112964).