CWE
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CWE-644 Individual Dictionary Definition (Draft 9)

Insufficient Filtering of HTTP Headers for Scripting Syntax
Weakness ID
Status: Incomplete

644 (Weakness Variant)

Description

Summary

If an application fails to filter or escape 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. This weakness may also enable the 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.

Likelihood of Exploit

High

Common Consequences

Run Arbitrary Code

Information Leakage

Privilege Escalation

Enabling Factors for Exploitation

Script execution functionality is enabled in the user's browser.

Potential Mitigations

Perform output validation in order to filter/escape/encode unsafe data that is being passed from the server in an HTTP response header.

Disable script execution functionality in the clients' browser.

Observed Examples
ReferenceDescription
CVE-2006-3918: Summary: http_protocol.c in (1) IBM HTTP Server 6.0 before 6.0.2.13 and 6.1 before 6.1.0.1, and (2) Apache HTTP Server 1.3 before 1.3.35, 2.0 before 2.0.58, and 2.2 before 2.2.2, does not sanitize the Expect header from an HTTP request when it is reflected back in an error message, which might allow cross-site scripting (XSS) style attacks using web client components that can send arbitrary headers in requests, as demonstrated using a Flash SWF file.
Relationships
NatureTypeIDName
ChildOfWeakness ClassWeakness ClassWeakness Class116Incorrect Output Sanitization
Applicable Platforms

All

Time of Introduction

Architecture and Design

Implementation

Page Last Updated: April 22, 2008