Secunia Research has discovered two vulnerabilities in Citrix Access Gateway Plug-in for Windows, which can be exploited by malicious people to compromise a user's system.

1) A boundary error in the nsepacom ActiveX control (nsepa.exe) when processing HTTP responses based on the request via the "StartEpa()" method can be exploited to cause a heap-based buffer overflow via an overly long "CSEC" HTTP response header.

2) An integer overflow error in the nsepacom ActiveX control (nsepa.exe) when processing HTTP responses based on the request via the "StartEpa()" method can be exploited to cause a heap-based buffer overflow via a specially crafted "Content-Length" HTTP response header.

Successful exploitation of the vulnerabilities allows execution of arbitrary code.

The vulnerabilities are confirmed in version 9.3.49.5 and reportedly affect the following versions:
* 10.0 prior to 10.0-69.4
* 9.3 prior to 9.3-57.5
* 9.2 (all versions)
* 9.1 (all versions)
* 9.0 (all versions)

Solution
Update to version 10.0-69.4 or 9.3-57.5.
Further details available to Secunia VIM customers

Provided and/or discovered by
Dmitriy Pletnev, Secunia Research.

Changelog
Further details available to Secunia VIM customers

Original Advisory
Secunia Research:
http://secunia.com/secunia_research/2012-26/
http://secunia.com/secunia_research/2012-27/

Citrix:
http://support.citrix.com/article/CTX134303

Technical Analysis
Further details available to Secunia VIM customers

Alternate/detailed remediation
Further details available in Customer Area

Deep Links
Links available to Secunia VIM customers