A vulnerability in the web UI of Cisco Firepower Management Center (FMC) Software could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a user of the web-based management interface of the FMC Software. The vulnerability is due to insufficient validation of user-supplied input by the web-based management interface. An attacker could exploit this vulnerability by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the interface or to access sensitive, browser-based information.
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmcxss-UT3bMx9k