The application does not neutralize or incorrectly neutralizes web scripting syntax in HTTP headers that can be used by web browser components that can process raw headers, such as Flash. An attacker may be able to conduct cross-site scripting and other attacks against users who have these components enabled. If an application does not neutralize user controlled data being placed in the header of an HTTP response coming from the server, the header may contain a script that will get executed in the client's browser context, potentially resulting in a cross site scripting vulnerability or possibly an HTTP response splitting attack. It is important to carefully control data that is being placed both in HTTP response header and in the HTTP response body to ensure that no scripting syntax is present, taking various encodings into account. 1000 699 Weakness ChildOf 116 699 Category ChildOf 442 711 Category ChildOf 725 888 Category ChildOf 896 Architecture and Design Implementation Script execution functionality is enabled in the user's browser. High Integrity Confidentiality Availability Execute unauthorized code or commands Run arbitrary code. Confidentiality Read application data Attackers may be able to obtain sensitive information. Architecture and Design Perform output validation in order to filter/escape/encode unsafe data that is being passed from the server in an HTTP response header. Architecture and Design Disable script execution functionality in the clients' browser. In the following Java example, user-controlled data is added to the HTTP headers and returned to the client. Given that the data is not subject to neutralization, a malicious user may be able to inject dangerous scripting tags that will lead to script execution in the client browser. Java response.addHeader(HEADER_NAME, untrustedRawInputData); CVE-2006-3918 Web server does not remove the Expect header from an HTTP request when it is reflected back in an error message, allowing a Flash SWF file to perform XSS attacks. Evgeny Lebanidze Cigital 2008-01-30 Sean Eidemiller Cigital 2008-07-01 added/updated demonstrative examples CWE Content Team MITRE 2008-09-08 updated Common_Consequences, Relationships, Observed_Example CWE Content Team MITRE 2008-10-14 updated Description, Name, Observed_Examples, Relationships CWE Content Team MITRE 2009-03-10 updated Relationships CWE Content Team MITRE 2009-05-27 updated Description, Name CWE Content Team MITRE 2009-10-29 updated Common_Consequences CWE Content Team MITRE 2010-04-05 updated Description, Name CWE Content Team MITRE 2010-06-21 updated Demonstrative_Examples, Description, Observed_Examples CWE Content Team MITRE 2010-12-13 updated Common_Consequences CWE Content Team MITRE 2011-03-29 updated Description CWE Content Team MITRE 2011-06-01 updated Common_Consequences CWE Content Team MITRE 2012-05-11 updated Relationships CWE Content Team MITRE 2012-10-30 updated Potential_Mitigations Insufficient Filtering of HTTP Headers for Scripting Syntax Insufficient Sanitization of HTTP Headers for Scripting Syntax Improper Sanitization of HTTP Headers for Scripting Syntax