CVE-2022-20740

A vulnerability in the web-based management interface of Cisco Firepower Management Center (FMC) Software could allow an unauthenticated, remote attacker to conduct a cross-site scripting attack. This vulnerability is due to improper validation of user-supplied input to the web-based management interface. An attacker could exploit this vulnerability by convincing a user to click a link designed to pass malicious input to the interface. A successful exploit could allow the attacker to conduct cross-site scripting attacks and gain access to sensitive browser-based information.

Weakness

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as “<”, “>”, and “&” that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.

Affected Software

Potential Mitigations

• Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
• The problem of inconsistent output encodings often arises in web pages. If an encoding is not specified in an HTTP header, web browsers often guess about which encoding is being used. This can open up the browser to subtle XSS attacks.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/18.html
• https://cwe.mitre.org/data/definitions/193.html
• https://cwe.mitre.org/data/definitions/32.html
• https://cwe.mitre.org/data/definitions/86.html

References

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-xss-SfpEcvGT
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-xss-SfpEcvGT