The Secure ACS, which controls such things as routers in large networks, firewalls and wireless networks and a security advisory was issued after the China-based Network Security (NS) Focus Information Technology team discovered a buffer overflow.
The problem can cause service to hang or to restart, the NS advisory said. "With carefully crafted data [an] attacker could run arbitrary code with CSAdmin process privilege on the server."
The hacker could potentially seize control of the Cisco service when it is running on Windows.
"Exploitation of this vulnerability results in denial of service, and can potentially result in system administrator access," Cisco said in its advisory.
Cisco is providing repair software and customers are recommended to install patches or upgrade at their earliest possibility, Cisco said. Patch files are currently available on the company’s website and customers can download the fixes.
Versions of the ACS affected by the vulnerability include 2.6.4, 3.0.3 and 3.1.1.
The advisory can be found at www.cisco.com/warp/public/707/cisco-sa-20030423-ACS.shtml.